diff --git a/plugins/data/data_command.lua b/plugins/data/data_command.lua
index cd265d25b79..910a20beadc 100644
--- a/plugins/data/data_command.lua
+++ b/plugins/data/data_command.lua
@@ -1,13 +1,16 @@
 local dat = {}
+
 local info, ver
-local datread = require("data/load_dat")
+local datread = require('data/load_dat')
 do
 	local buttonchar
 	local function convert(str)
-		if not buttonchar then buttonchar = require("data/button_char") end
+		if not buttonchar then
+			buttonchar = require("data/button_char")
+		end
 		return buttonchar(str)
 	end
-	datread, ver = datread.open("command.dat", "#[^V]*Ver[^.:]*[.:]", convert)
+	datread, ver = datread.open('command.dat', '#[^V]*Ver[^.:]*[.:]', convert)
 end
 
 function dat.check(set, softlist)
@@ -15,11 +18,11 @@ function dat.check(set, softlist)
 		return nil
 	end
 	local status
-	status, info = pcall(datread, "cmd", "info", set)
+	status, info = pcall(datread, 'cmd', 'info', set)
 	if not status or not info then
 		return nil
 	end
-	return _p("plugin-data", "Command")
+	return _p('plugin-data', 'Command')
 end
 
 function dat.get()
diff --git a/plugins/data/data_gameinit.lua b/plugins/data/data_gameinit.lua
index 31e659325c4..f6856629bb8 100644
--- a/plugins/data/data_gameinit.lua
+++ b/plugins/data/data_gameinit.lua
@@ -1,19 +1,19 @@
 local dat = {}
-local ver, info
 
-local datread = require("data/load_dat")
-datread, ver = datread.open("gameinit.dat", "# .-GAMEINIT.DAT")
+local ver, info
+local datread = require('data/load_dat')
+datread, ver = datread.open('gameinit.dat', '# .-GAMEINIT.DAT')
 
 function dat.check(set, softlist)
 	if softlist or not datread then
 		return nil
 	end
 	local status
-	status, info = pcall(datread, "mame", "info", set)
+	status, info = pcall(datread, 'mame', 'info', set)
 	if not status or not info then
 		return nil
 	end
-	return _p("plugin-data", "Gameinit")
+	return _p('plugin-data', 'Gameinit')
 end
 
 function dat.get()
diff --git a/plugins/data/data_history.lua b/plugins/data/data_history.lua
index e6fd4eb2509..b233405e984 100644
--- a/plugins/data/data_history.lua
+++ b/plugins/data/data_history.lua
@@ -1,149 +1,178 @@
 local dat = {}
-local db = require("data/database")
+
+local db = require('data/database')
 local ver, info
-local file = "history.xml"
+local file = 'history.xml'
+local tablename
 
 local function init()
-	local filepath
-	local dbver
-	local fh
-
-	for path in mame_manager.ui.options.entries.historypath:value():gmatch("([^;]+)") do
-		filepath = emu.subst_env(path) .. "/" .. file
-		fh = io.open(filepath, "r")
-		if fh then
-			break
-		end
-	end
-
 	-- check for old history table
-	local stmt = db.prepare("SELECT version FROM version WHERE datfile = ?")
-	stmt:bind_values("history.dat")
-	if stmt:step() == db.ROW then
-		stmt:finalize()
-		db.exec("DROP TABLE \"history.dat\"")
-		db.exec("DROP TABLE \"history.dat_idx\"")
-		stmt = db.prepare("DELETE FROM version WHERE datfile = ?")
-		stmt:bind_values("history.dat")
-		stmt:step()
+	if db.get_version('history.dat') then
+		db.exec([[DROP TABLE "history.dat";]])
+		db.exec([[DROP TABLE "history.dat_idx";]])
+		db.set_version('history.dat', nil)
 	end
-	stmt:finalize()
 
-
-	local stmt = db.prepare("SELECT version FROM version WHERE datfile = ?")
-	db.check("reading history version")
-	stmt:bind_values(file)
-	if stmt:step() == db.ROW then
-		dbver = stmt:get_value(0)
-	end
-	stmt:finalize()
-
-	if not fh and dbver then
-		-- data in database but missing file, just use what we have
-		ver = dbver
+	local fh, filepath, dbver
+	fh, filepath, tablename, dbver = db.open_data_file(file)
+	if not fh then
+		if dbver then
+			-- data in database but missing file, just use what we have
+			ver = dbver
+		end
 		return
-	elseif not fh then
-		return
-	elseif not dbver then
-		db.exec("CREATE TABLE \"" .. file .. [[_idx" (
-				name VARCHAR NOT NULL,
-				list VARCHAR,
-				data INTEGER NOT NULL)]])
-		db.check("creating index")
-		db.exec("CREATE TABLE \"" .. file .. "\" (data CLOB NOT NULL)")
-		db.check("creating table")
-		db.exec("CREATE INDEX \"name_" .. file .. "\" ON \"" .. file .. "_idx\"(name)")
-		db.check("creating system index")
 	end
 
+	-- scan file for version
 	for line in fh:lines() do
-		local match = line:match("<history([^>]*)>")
+		local match = line:match('<history([^>]*)>')
 		if match then
-			match = match:match("version=\"([^\"]*)\"")
+			match = match:match('version="([^"]*)"')
 			if match then
 				ver = match
 				break
 			end
 		end
 	end
-
-	if not ver then
+	if (not ver) or (ver == dbver) then
 		fh:close()
+		ver = dbver
 		return
 	end
 
-	if ver == dbver then
+	if not dbver then
+		db.exec(
+			string.format(
+				[[CREATE TABLE "%s_idx" (
+					name VARCHAR NOT NULL,
+					list VARCHAR NOT NULL,
+					data INTEGER NOT NULL);]],
+				tablename))
+		db.check(string.format('creating %s index table', file))
+		db.exec(string.format([[CREATE TABLE "%s" (data CLOB NOT NULL);]], tablename))
+		db.check(string.format('creating %s data table', file))
+		db.exec(
+			string.format(
+				[[CREATE INDEX "namelist_%s" ON "%s_idx" (name, list);]],
+				tablename, tablename))
+		db.check(string.format('creating %s name/list index', file))
+	end
+
+	local slaxml = require('xml')
+
+	db.exec([[BEGIN TRANSACTION;]])
+	if not db.check(string.format('starting %s transaction', file)) then
 		fh:close()
+		ver = dbver
 		return
 	end
 
+	-- clean out previous data and update the version
 	if dbver then
-		db.exec("DELETE FROM \"" .. file .. "\"")
-		db.check("deleting history")
-		db.exec("DELETE FROM \"" .. file .. "_idx\"")
-		db.check("deleting index")
-		stmt = db.prepare("UPDATE version SET version = ? WHERE datfile = ?")
-		db.check("updating history version")
-	else
-		stmt = db.prepare("INSERT INTO version VALUES (?, ?)")
-		db.check("inserting history version")
+		db.exec(string.format([[DELETE FROM "%s";]], tablename))
+		if not db.check(string.format('deleting previous %s data', file)) then
+			db.exec([[ROLLBACK TRANSACTION;]])
+			fh:close()
+			ver = dbver
+			return
+		end
+		db.exec(string.format([[DELETE FROM "%s_idx";]], tablename))
+		if not db.check(string.format('deleting previous %s data', file)) then
+			db.exec([[ROLLBACK TRANSACTION;]])
+			fh:close()
+			ver = dbver
+			return
+		end
+	end
+	db.set_version(file, ver)
+	if not db.check(string.format('updating %s version', file)) then
+		db.exec([[ROLLBACK TRANSACTION;]])
+		fh:close()
+		ver = dbver
+		return
 	end
-	stmt:bind_values(ver, file)
-	stmt:step()
-	stmt:finalize()
 
-	fh:seek("set")
-	local buffer = fh:read("a")
-	db.exec("BEGIN TRANSACTION")
-	db.check("beginning history transation")
+	fh:seek('set')
+	local buffer = fh:read('a')
 
 	local lasttag
 	local entry = {}
 	local rowid
-	local slaxml = require("xml")
+
+	local dataquery = db.prepare(
+		string.format([[INSERT INTO "%s" (data) VALUES (?);]], tablename))
+	local indexquery = db.prepare(
+		string.format([[INSERT INTO "%s_idx" (name, list, data) VALUES (?, ?, ?);]], tablename))
 
 	local parser = slaxml:parser{
 		startElement = function(name)
 			lasttag = name
-			if name == "entry" then
+			if name == 'entry' then
 				entry = {}
 				rowid = nil
-			elseif (name == "system") or (name == "item") then
-				entry[#entry + 1] = {}
+			elseif (name == 'system') or (name == 'item') then
+				table.insert(entry, {})
 			end
 		end,
 		attribute = function(name, value)
-			if (name == "name") or (name == "list") then
+			if (name == 'name') or (name == 'list') then
 				entry[#entry][name] = value
 			end
 		end,
 		text = function(text, cdata)
-			if lasttag == "text" then
-				text = text:gsub("\r", "") -- strip crs
-				stmt = db.prepare("INSERT INTO \"" .. file .. "\" VALUES (?)")
-				db.check("inserting values")
-				stmt:bind_values(text)
-				stmt:step()
-				rowid = stmt:last_insert_rowid()
-				stmt:finalize()
+			if lasttag == 'text' then
+				text = text:gsub('\r', '') -- strip carriage returns
+				dataquery:bind_values(text)
+				while true do
+					local status = dataquery:step()
+					if status == db.DONE then
+						rowid = dataquery:last_insert_rowid();
+						break
+					elseif result == db.BUSY then
+						emu.print_error(string.format('Database busy: inserting %s data', file))
+						-- FIXME: how to abort parse and roll back?
+						break
+					elseif result ~= db.ROW then
+						db.check(string.format('inserting %s data', file))
+						break
+					end
+				end
+				dataquery:reset()
 			end
 		end,
 		closeElement = function(name)
-			if name == "entry" then
+			if (name == 'entry') and rowid then
 				for num, entry in pairs(entry) do
-					stmt = db.prepare("INSERT INTO \"" .. file .. "_idx\" VALUES (?, ?, ?)")
-					db.check("inserting into index")
-					stmt:bind_values(entry.name, entry.list, rowid)
-					stmt:step()
-					stmt:finalize()
+					indexquery:bind_values(entry.name, entry.list or '', rowid)
+					while true do
+						local status = indexquery:step()
+						if status == db.DONE then
+							break
+						elseif status == db.BUSY then
+							emu.print_error(string.format('Database busy: inserting %s data', file))
+							-- FIXME: how to abort parse and roll back?
+							break
+						elseif result ~= db.ROW then
+							db.check(string.format('inserting %s data', file))
+							break
+						end
+					end
+					indexquery:reset()
 				end
 			end
 		end
 	}
-	parser:parse(buffer, {stripWhitespace=true})
+
+	parser:parse(buffer, { stripWhitespace = true })
+	dataquery:finalize()
+	indexquery:finalize()
 	fh:close()
-	db.exec("END TRANSACTION")
-	db.check("ending history transation")
+
+	db.exec([[COMMIT TRANSACTION;]])
+	if not db.check(string.format('committing %s transaction', file)) then
+		db.exec([[ROLLBACK TRANSACTION;]])
+		ver = dbver
+	end
 end
 
 if db then
@@ -151,25 +180,31 @@ if db then
 end
 
 function dat.check(set, softlist)
-	if not ver or not db then
+	if not ver then
 		return nil
 	end
+
 	info = nil
-	local stmt
-	if softlist then
-		stmt = db.prepare("SELECT f.data FROM \"" .. file .. "_idx\" AS fi, \"" .. file .. [["
-			AS f WHERE fi.name = ? AND fi.list = ? AND f.rowid = fi.data]])
-		stmt:bind_values(set, softlist)
-	else
-		stmt = db.prepare("SELECT f.data FROM \"" .. file .. "_idx\" AS fi, \"" .. file .. [["
-			AS f WHERE fi.name = ? AND fi.list ISNULL AND f.rowid = fi.data]])
-		stmt:bind_values(set)
+	local query = db.prepare(
+		string.format(
+			[[SELECT f.data
+				FROM "%s_idx" AS fi LEFT JOIN "%s" AS f ON fi.data = f.rowid
+				WHERE fi.name = ? AND fi.list = ?;]],
+			tablename, tablename))
+	query:bind_values(set, softlist or '')
+	while not info do
+		local status = query:step()
+		if status == db.ROW then
+			info = query:get_value(0)
+		elseif status == db.DONE then
+			break
+		elseif status ~= db.BUSY then
+			db.check(string.format('reading %s data', file))
+			break
+		end
 	end
-	if stmt:step() == db.ROW then
-		info = stmt:get_value(0)
-	end
-	stmt:finalize()
-	return info and _p("plugin-data", "History") or nil
+	query:finalize()
+	return info and _p('plugin-data', 'History') or nil
 end
 
 function dat.get()
diff --git a/plugins/data/data_mameinfo.lua b/plugins/data/data_mameinfo.lua
index 7a6e6ea2def..0e77e328cef 100644
--- a/plugins/data/data_mameinfo.lua
+++ b/plugins/data/data_mameinfo.lua
@@ -1,23 +1,27 @@
 local dat = {}
-local ver, info
-local datread = require("data/load_dat")
-datread, ver = datread.open("mameinfo.dat", "# MAMEINFO.DAT", function(str) return str:gsub("\n\n", "\n") end)
+
+local info, ver
+local datread = require('data/load_dat')
+datread, ver = datread.open(
+	'mameinfo.dat',
+	'# MAMEINFO.DAT',
+	function (str) return str:gsub('\n\n', '\n') end)
 
 function dat.check(set, softlist)
 	if softlist or not datread then
 		return nil
 	end
 	local status, drvinfo
-	status, info = pcall(datread, "mame", "info", set)
+	status, info = pcall(datread, 'mame', 'info', set)
 	if not status or not info then
 		return nil
 	end
-	local sourcefile = emu.driver_find(set).source_file:match("[^/\\]*$")
-	status, drvinfo = pcall(datread, "drv", "info", sourcefile)
+	local sourcefile = emu.driver_find(set).source_file:match('[^/\\]*$')
+	status, drvinfo = pcall(datread, 'drv', 'info', sourcefile)
 	if drvinfo then
-		info = info .. _p("plugin-data", "\n\n--- DRIVER INFO ---\nDriver: ") .. sourcefile .. "\n\n" .. drvinfo
+		info = info .. _p('plugin-data', '\n\n--- DRIVER INFO ---\nDriver: ') .. sourcefile .. '\n\n' .. drvinfo
 	end
-	return _p("plugin-data", "MAMEinfo")
+	return _p('plugin-data', 'MAMEinfo')
 end
 
 function dat.get()
diff --git a/plugins/data/data_marp.lua b/plugins/data/data_marp.lua
index 47a45785a81..09fddf11ef9 100644
--- a/plugins/data/data_marp.lua
+++ b/plugins/data/data_marp.lua
@@ -1,120 +1,144 @@
 -- get marp high score file from http://replay.marpirc.net/txt/scores3.htm
 local dat = {}
+
 local db = require("data/database")
 local ver, info
 
 local function init()
-	local filepath
-	local dbver
-	local fh
-	local file = "scores3.htm"
+	local file = 'scores3.htm'
 
-	for path in mame_manager.ui.options.entries.historypath:value():gmatch("([^;]+)") do
-		filepath = emu.subst_env(path) .. "/" .. file
-		fh = io.open(filepath, "r")
-		if fh then
-			break
+	local fh, filepath, tablename, dbver = db.open_data_file(file)
+	if not fh then
+		if dbver then
+			-- data in database but missing file, just use what we have
+			ver = dbver
 		end
-	end
-
-	local stmt = db.prepare("SELECT version FROM version WHERE datfile = ?")
-	db.check("reading marp version")
-	stmt:bind_values(file)
-	if stmt:step() == db.ROW then
-		dbver = stmt:get_value(0)
-	end
-	stmt:finalize()
-
-	if not fh and dbver then
-		-- data in database but missing file, just use what we have
-		ver = dbver
 		return
-	elseif not fh then
-		return
-	elseif not dbver then
-		db.exec("CREATE TABLE \"" .. file .. [[" (
-		romset VARCHAR NOT NULL,
-		data CLOB NOT NULL)]])
-		db.check("creating marp table")
 	end
 
+	-- scan file for version
 	for line in fh:lines() do
-		local match = line:match("Top Scores from the MAME Action Replay Page %(([%w :]+)%)")
+		local match = line:match('Top Scores from the MAME Action Replay Page %(([%w :]+)%)')
 		if match then
 			ver = match
 			break
 		end
 	end
-
-	if not ver then
+	if (not ver) or (ver == dbver) then
 		fh:close()
+		ver = dbver
 		return
 	end
 
-	if ver == dbver then
+	if not dbver then
+		db.exec(
+			string.format(
+				[[CREATE TABLE "%s" (
+					romset VARCHAR NOT NULL,
+					data CLOB NOT NULL,
+					PRIMARY KEY(romset));]],
+				tablename))
+		db.check('creating MARP table')
+	end
+
+	db.exec([[BEGIN TRANSACTION;]])
+	if not db.check('starting MARP transaction') then
 		fh:close()
+		ver = dbver
 		return
 	end
 
+	-- clean out previous data and update the version
 	if dbver then
-		db.exec("DELETE FROM \"" .. file .. "\"")
-		db.check("deleting marp")
-		stmt = db.prepare("UPDATE version SET version = ? WHERE datfile = ?")
-		db.check("updating marp version")
-	else
-		stmt = db.prepare("INSERT INTO version VALUES (?, ?)")
-		db.check("inserting marp version")
+		db.exec(string.format([[DELETE FROM "%s";]], tablename))
+		if not db.check('deleting previous MARP data') then
+			db.exec([[ROLLBACK TRANSACTION;]])
+			fh:close()
+			ver = dbver
+			return
+		end
+	end
+	if not db.set_version(file, ver) then
+		db.check('updating MARP version')
+		db.exec([[ROLLBACK TRANSACTION;]])
+		fh:close()
+		ver = dbver
+		return
 	end
-	stmt:bind_values(ver, file)
-	stmt:step()
-	stmt:finalize()
 
-	fh:seek("set")
-	local buffer = fh:read("a")
-	db.exec("BEGIN TRANSACTION")
-	db.check("beginning marp transation")
+	fh:seek('set')
+	local buffer = fh:read('a')
 
 	local function gmatchpos()
 		local pos = 1
-		local set, data = ""
+		local set = ''
+		local data = ''
 		local function iter()
 			local lastset = set
 			while true do
 				local spos, scr, plyr, stype, ltype
-				local url = ""
-				spos, pos, set, stype, scr, plyr, ltype = buffer:find("\n%s*([%w_]*)%-?(%w-) :%s*(%d+) [;:] ([^:]+): [^%[\n]*%[?([%w ]*)[^\n]*", pos)
+				spos, pos, set, stype, scr, plyr, ltype = buffer:find('\n%s*([%w_]*)%-?(%w-) :%s*(%d+) [;:] ([^:]+): [^%[\n]*%[?([%w ]*)[^\n]*', pos)
 				if not spos then
 					return nil
 				end
-				if set ~= "" then
-					if ltype ~= "" then
-						url = ltype .. "\t\n"
-					else
-						url = ""
+
+				local url = ''
+				if set ~= '' then
+					if ltype ~= '' then
+						url = ltype .. '\t\n'
 					end
-					url = url .. "http://replay.marpirc.net/r/" .. set .. ((stype ~= "") and ("-" .. stype) or "") .. "\t\n"
+					url = url .. 'http://replay.marpirc.net/r/' .. set
+					if stype ~= '' then
+						url = url .. '-' .. stype
+					end
+					url = url .. '\t\n'
 				end
-				if set ~= "" and lastset and lastset ~= set then
+
+				if (set ~= '') and (lastset ~= set) then
 					local lastdata = data
-					data = url .. plyr .. "\t" .. scr .. "\n"
+					data = url .. plyr .. '\t' .. scr .. '\n'
 					return lastset, lastdata
 				end
-				data = data .. ((url ~= "") and ("\n" .. url) or "") .. plyr .. "\t" .. scr .. "\n"
+
+				if url ~= '' then
+					data = data .. '\n' .. url
+				end
+				data = data .. plyr .. '\t' .. scr .. '\n'
 			end
 		end
 		return iter
 	end
 
+	local query = db.prepare(
+		string.format([[INSERT INTO "%s" (romset, data) VALUES (?, ?)]], tablename))
 	for set, data in gmatchpos() do
-		stmt = db.prepare("INSERT INTO \"" .. file .. "\" VALUES (?, ?)")
-		db.check("inserting marp values")
-		stmt:bind_values(set, data)
-		stmt:step()
-		stmt:finalize()
+		query:bind_values(set, data)
+		while true do
+			local status = query:step()
+			if status == db.DONE then
+				break
+			elseif status == db.BUSY then
+				emu.print_error('Database busy: inserting MARP data')
+				query:finalize()
+				db.exec([[ROLLBACK TRANSACTION;]])
+				fh:close()
+				ver = dbver
+				return
+			elseif result ~= db.ROW then
+				db.check('inserting MARP data')
+				break
+			end
+		end
+		query:reset()
 	end
+	query:finalize()
+
 	fh:close()
-	db.exec("END TRANSACTION")
-	db.check("ending marp transation")
+	db.exec([[COMMIT TRANSACTION;]])
+	if not db.check('committing MARP transaction') then
+		db.exec([[ROLLBACK TRANSACTION;]])
+		ver = dbver
+	end
 end
 
 if db then
@@ -122,18 +146,26 @@ if db then
 end
 
 function dat.check(set, softlist)
-	if softlist or not ver or not db then
+	if softlist or (not ver) then
 		return nil
 	end
+
 	info = nil
-	local stmt = db.prepare("SELECT data FROM \"scores3.htm\" AS f WHERE romset = ?")
-	db.check("reading marp data")
-	stmt:bind_values(set)
-	if stmt:step() == db.ROW then
-		info = "#j2\n" .. stmt:get_value(0)
+	local query = db.prepare([[SELECT data FROM "scores3.htm" WHERE romset = ?;]])
+	query:bind_values(set)
+	while not info do
+		local status = query:step()
+		if status == db.ROW then
+			info = '#j2\n' .. query:get_value(0)
+		elseif status == db.DONE then
+			break
+		elseif status ~= db.BUSY then
+			db.check('reading MARP data')
+			break
+		end
 	end
-	stmt:finalize()
-	return info and _p("plugin-data", "MARPScore") or nil
+	query:finalize()
+	return info and _p('plugin-data', 'MARPScore') or nil
 end
 
 function dat.get()
diff --git a/plugins/data/data_messinfo.lua b/plugins/data/data_messinfo.lua
index fe2099890ee..3c94322474f 100644
--- a/plugins/data/data_messinfo.lua
+++ b/plugins/data/data_messinfo.lua
@@ -1,24 +1,27 @@
 local dat = {}
-local ver, info
 
-local datread = require("data/load_dat")
-datread, ver = datread.open("messinfo.dat", "#     MESSINFO.DAT", function(str) return str:gsub("\n\n", "\n") end)
+local ver, info
+local datread = require('data/load_dat')
+datread, ver = datread.open(
+	'messinfo.dat',
+	'#     MESSINFO.DAT',
+	function (str) return str:gsub('\n\n', '\n') end)
 
 function dat.check(set, softlist)
 	if softlist or not datread then
 		return nil
 	end
 	local status, drvinfo
-	status, info = pcall(datread, "mame", "info", set)
+	status, info = pcall(datread, 'mame', 'info', set)
 	if not status or not info then
 		return nil
 	end
-	local sourcefile = emu.driver_find(set).source_file:match("[^/\\]*$")
-	status, drvinfo = pcall(datread, "drv", "info", sourcefile)
+	local sourcefile = emu.driver_find(set).source_file:match('[^/\\]*$')
+	status, drvinfo = pcall(datread, 'drv', 'info', sourcefile)
 	if drvinfo then
-		info = info .. _p("plugin-data", "\n\n--- DRIVER INFO ---\nDriver: ") .. sourcefile .. "\n\n" .. drvinfo
+		info = info .. _p('plugin-data', '\n\n--- DRIVER INFO ---\nDriver: ') .. sourcefile .. '\n\n' .. drvinfo
 	end
-	return _p("plugin-data", "MESSinfo")
+	return _p('plugin-data', 'MESSinfo')
 end
 
 function dat.get()
diff --git a/plugins/data/data_story.lua b/plugins/data/data_story.lua
index 70bedd02df0..b17bb4f1ea1 100644
--- a/plugins/data/data_story.lua
+++ b/plugins/data/data_story.lua
@@ -1,25 +1,26 @@
 local dat = {}
+
 local ver, info
-local datread = require("data/load_dat")
-datread, ver = datread.open("story.dat", "# version")
+local datread = require('data/load_dat')
+datread, ver = datread.open('story.dat', '# version')
 
 function dat.check(set, softlist)
 	if softlist or not datread then
 		return nil
 	end
-	local status, data = pcall(datread, "story", "info", set)
+	local status, data = pcall(datread, 'story', 'info', set)
 	if not status or not data then
 		return nil
 	end
 	local lines = {}
-	data = data:gsub("MAMESCORE records : ([^\n]+)", "MAMESCORE records :\t\n%1", 1)
-	for line in data:gmatch("[^\n]*") do
-		if not (#lines == 0 and line == "") and not (lines[#lines] == "" and line == "") then
-			lines[#lines + 1] = line:gsub("^(.-)_+([0-9.]+)$", "%1\t%2")
+	data = data:gsub('MAMESCORE records : ([^\n]+)', 'MAMESCORE records :\t\n%1', 1)
+	for line in data:gmatch('[^\n]*') do
+		if (line ~= '') or ((#lines ~= 0) and (lines[#lines] ~= '')) then
+			table.insert(lines, line:gsub('^(.-)_+([0-9.]+)$', '%1\t%2'))
 		end
 	end
-	info = "#j2\n" .. table.concat(lines, "\n")
-	return _p("plugin-data", "Mamescore")
+	info = '#j2\n' .. table.concat(lines, '\n')
+	return _p('plugin-data', 'Mamescore')
 end
 
 function dat.get()
diff --git a/plugins/data/data_sysinfo.lua b/plugins/data/data_sysinfo.lua
index cb2daaa03a0..1ba13605821 100644
--- a/plugins/data/data_sysinfo.lua
+++ b/plugins/data/data_sysinfo.lua
@@ -1,18 +1,19 @@
 local dat = {}
+
 local ver, info
-local datread = require("data/load_dat")
-datread, ver = datread.open("sysinfo.dat", "# This file was generated on")
+local datread = require('data/load_dat')
+datread, ver = datread.open('sysinfo.dat', '# This file was generated on')
 
 function dat.check(set, softlist)
 	if softlist or not datread then
 		return nil
 	end
 	local status
-	status, info = pcall(datread, "bio", "info", set)
+	status, info = pcall(datread, 'bio', 'info', set)
 	if not status or not info then
 		return nil
 	end
-	return _p("plugin-data", "Sysinfo")
+	return _p('plugin-data', 'Sysinfo')
 end
 
 function dat.get()
diff --git a/plugins/data/database.lua b/plugins/data/database.lua
index be52f23ee63..e0249182409 100644
--- a/plugins/data/database.lua
+++ b/plugins/data/database.lua
@@ -1,41 +1,159 @@
-local sql = require("lsqlite3")
-local datfile = {}
+local sql = require('lsqlite3')
 local db
 
-local function check_db(msg)
+local function check_db_result(msg)
 	if db:errcode() > sql.OK then
-		emu.print_error(string.format("Error: %s (%s - %s)", msg, db:errcode(), db:errmsg()))
+		emu.print_error(string.format('Error: %s (%s - %s)', msg, db:errcode(), db:errmsg()))
+		return false
 	end
+	return true
 end
 
-do
-	local dbpath = emu.subst_env(mame_manager.ui.options.entries.historypath:value():match("([^;]+)"))
-	db = sql.open(dbpath .. "/history.db")
-	if not db then
-		lfs.mkdir(dbpath)
-		db = sql.open(dbpath .. "/history.db")
-		if not db then
-			emu.print_error("Unable to create history.db")
-			return false
-		end
-		check_db("opening database")
-	end
+local function settings_path()
+	return emu.subst_env(manager.machine.options.entries.homepath:value():match('([^;]+)')) .. '/data'
 end
 
-if db then
+local function check_version_table()
 	local found = false
-	db:exec("select * from sqlite_master where name = 'version'", function() found = true return 0 end)
-	check_db("checking for 'version' table")
+	db:exec(
+			[[SELECT COUNT(*) FROM sqlite_master WHERE name = 'version' AND type = 'table';]],
+			function (udata, cols, values, names)
+				found = tonumber(values[1]) > 0
+				return 0
+			end)
+	if check_db_result('checking for "version" table') and (not found) then
+		db:exec(
+				[[CREATE TABLE version (
+					datfile VARCHAR NOT NULL,
+					version VARCHAR NOT NULL,
+					PRIMARY KEY (datfile));]])
+		found = check_db_result('creating "version" table')
+	end
 	if not found then
-		db:exec([[
-			CREATE TABLE version (
-				version VARCHAR NOT NULL,
-				datfile VARCHAR UNIQUE NOT NULL)]])
-		check_db("creating 'version' table")
+		db:close()
+		db = nil
 	end
 end
 
-local dbtable = { prepare = function(...) return db:prepare(...) end,
-		  exec = function(...) return db:exec(...) end, ROW = sql.ROW, check = check_db }
+local function open_existing()
+	db = sql.open(settings_path() .. '/history.db', sql.OPEN_READWRITE)
+	if db then
+		check_version_table()
+	end
+	return db
+end
 
-return db and dbtable or false
+local function open_create()
+	-- first try to create settings directory
+	local dir = settings_path()
+	local attr = lfs.attributes(dir)
+	if (not attr) and (not lfs.mkdir(dir)) then
+		emu.print_error(string.format('Error creating data plugin settings directory "%s"', dir))
+	elseif attr and (attr.mode ~= 'directory') then
+		emu.print_error(string.format('Error opening data plugin database: "%s" is not a directory', dir))
+	else
+		-- now try to open the database
+		local dbpath = dir .. '/history.db'
+		db = sql.open(dbpath, sql.OPEN_READWRITE | sql.OPEN_CREATE)
+		if not db then
+			emu.print_error(string.format('Error opening data plugin database "%s"', dbpath))
+		else
+			check_version_table()
+		end
+	end
+	return db
+end
+
+
+local dbtable = {
+	ROW = sql.ROW,
+	BUSY = sql.BUSY,
+	DONE = sql.DONE,
+	check = check_db_result }
+
+function dbtable.sanitize_name(name)
+	return name:gsub('[^%w%."]', '_')
+end
+
+function dbtable.get_version(filename)
+	-- don't try to create the database here, just return nil if it doesn't exist
+	if (not db) and (not open_existing()) then
+		return nil
+	end
+	local query = db:prepare([[SELECT version FROM version WHERE datfile = ?;]])
+	query:bind_values(filename)
+	local result
+	while result == nil do
+		local status = query:step()
+		if status == sql.ROW then
+			result = query:get_value(0)
+		elseif status ~= sql.BUSY then
+			break
+		end
+	end
+	query:finalize()
+	return result
+end
+
+function dbtable.set_version(filename, version)
+	if (not db) and (not open_create()) then
+		return nil
+	end
+	local query
+	if version ~= nil then
+		query = db:prepare(
+			[[INSERT INTO version (datfile, version) VALUES (?1, ?2)
+				ON CONFLICT(datfile) DO UPDATE set version = ?2;]])
+		query:bind_values(filename, version)
+	else
+		query = db:prepare([[DELETE FROM version WHERE datfile = ?1;]])
+		query:bind_values(filename)
+	end
+	local result
+	while result == nil do
+		local status = query:step()
+		if status == sqlite3.DONE then
+			result = true
+		elseif result ~= sqlite3.ROW then
+			result = false
+		end
+	end
+	query:finalize()
+	return result
+end
+
+function dbtable.prepare(...)
+	if (not db) and open_create() then
+		dbtable.prepare = function (...) return db:prepare(...) end
+	end
+	if db then
+		return db:prepare(...)
+	else
+		return nil
+	end
+end
+
+function dbtable.exec(...)
+	if (not db) and open_create() then
+		dbtable.exec = function (...) return db:exec(...) end
+	end
+	if db then
+		return db:exec(...)
+	else
+		return nil
+	end
+end
+
+function dbtable.open_data_file(file)
+	local fh, filepath
+	for path in mame_manager.ui.options.entries.historypath:value():gmatch('([^;]+)') do
+		filepath = emu.subst_env(path) .. '/' .. file
+		fh = io.open(filepath, 'r')
+		if fh then
+			break
+		end
+	end
+	return fh, filepath, dbtable.sanitize_name(file), dbtable.get_version(file)
+end
+
+return dbtable
diff --git a/plugins/data/init.lua b/plugins/data/init.lua
index f58742e8d34..eb3ad1ae9b3 100644
--- a/plugins/data/init.lua
+++ b/plugins/data/init.lua
@@ -4,12 +4,12 @@
 -- heading if it supports the set otherwise nil and get which returns the data
 -- the script should be named data_<name>.lua
 -- this is set default on in the plugin.json
-local exports = {}
-exports.name = "data"
-exports.version = "0.0.1"
-exports.description = "Data plugin"
-exports.license = "BSD-3-Clause"
-exports.author = { name = "Carl" }
+local exports = {
+	name = 'data',
+	version = '0.0.2',
+	description = 'Data plugin',
+	license = 'BSD-3-Clause',
+	author = { name = 'Carl' } }
 
 local data = exports
 
@@ -26,7 +26,7 @@ function data.startplugin()
 	local cur_list
 
 	emu.register_start(
-			function()
+			function ()
 				data_scr = {}
 				for file in lfs.dir(plugindir) do
 					local name = string.match(file, '^(data_.*).lua$')
@@ -40,7 +40,7 @@ function data.startplugin()
 			end)
 
 	emu.register_callback(
-			function(set)
+			function (set)
 				local ret = {}
 				if set == '' then
 					set = emu.romname()
@@ -70,13 +70,13 @@ function data.startplugin()
 			'data_list')
 
 	emu.register_callback(
-			function(num)
+			function (num)
 				return valid_lst[num + 1].get()
 			end,
 			'data')
 
 	emu.register_callback(
-			function(num)
+			function (num)
 				local ver
 				if valid_lst[num + 1].ver then
 					ver = valid_lst[num + 1].ver()
diff --git a/plugins/data/load_dat.lua b/plugins/data/load_dat.lua
index 7209872ad32..0438c5499ba 100644
--- a/plugins/data/load_dat.lua
+++ b/plugins/data/load_dat.lua
@@ -1,17 +1,29 @@
 local datfile = {}
-local db = require("data/database")
 
-local function readret(file)
-	local function read(tag1, tag2, set)
+local db = require('data/database')
+
+local function readret(file, tablename)
+	local query = db.prepare(
+		string.format(
+			[[SELECT f.data
+				FROM "%s_idx" AS fi LEFT JOIN "%s" AS f ON fi.data = f.rowid
+				WHERE fi.type = ? AND fi.val = ? AND fi.romset = ?;]],
+			tablename, tablename))
+	local function read(tag, val, set)
+		query:bind_values(tag, val, set)
 		local data
-		local stmt = db.prepare("SELECT f.data FROM \"" .. file .. "_idx\" AS fi, \"" .. file .. [["
-		AS f WHERE fi.type = ? AND fi.val = ? AND fi.romset = ? AND f.rowid = fi.data]])
-		db.check("reading " .. tag1 .. " - " .. tag2 .. " - " .. set)
-		stmt:bind_values(tag1, tag2, set)
-		if stmt:step() == db.ROW then
-			data = stmt:get_value(0)
+		while not data do
+			local status = query:step()
+			if status == db.ROW then
+				data = query:get_value(0)
+			elseif status == db.DONE then
+				break
+			elseif status ~= db.BUSY then
+				db.check(string.format('reading %s data', file))
+				break
+			end
 		end
-		stmt:finalize()
+		query:reset()
 		return data
 	end
 	return read
@@ -22,49 +34,22 @@ function datfile.open(file, vertag, fixupcb)
 	if not db then
 		return nil
 	end
-	local ver, dbver
-	local filepath
-	local fh
 
-	for path in mame_manager.ui.options.entries.historypath:value():gmatch("([^;]+)") do
-		filepath = emu.subst_env(path) .. "/" .. file
-		fh = io.open(filepath, "r")
-		if fh then
-			break
+	local fh, filepath, tablename, dbver = db.open_data_file(file)
+	if not fh then
+		if dbver then
+			-- data in database but missing file, just use what we have
+			return readret(file, tablename), dbver
+		else
+			return nil
 		end
 	end
-	-- remove unsafe chars from file for use in sql statement
-	file = file:gsub("[^%w%._]", "")
-
-	local stmt = db.prepare("SELECT version FROM version WHERE datfile = ?")
-	db.check("reading version")
-	stmt:bind_values(file)
-	if stmt:step() == db.ROW then
-		dbver = stmt:get_value(0)
-	end
-	stmt:finalize()
-
-	if not fh and dbver then
-		-- data in database but missing file, just use what we have
-		return readret(file), dbver
-	elseif not fh then
-		return nil
-	elseif not dbver then
-		db.exec("CREATE TABLE \"" .. file .. [[_idx" (
-				type VARCHAR NOT NULL,
-				val VARCHAR NOT NULL,
-				romset VARCHAR NOT NULL,
-				data INTEGER NOT NULL)]])
-		db.check("creating index")
-		db.exec("CREATE TABLE \"" .. file .. "\" (data CLOB NOT NULL)")
-		db.check("creating table")
-		db.exec("CREATE INDEX \"typeval_" .. file .. "\" ON \"" .. file .. "_idx\"(type, val)")
-		db.check("creating typeval index")
-	end
 
+	local ver
 	if vertag then
+		-- scan file for version
 		for line in fh:lines() do
-			local match = line:match(vertag .. "%s*(%S+)")
+			local match = line:match(vertag .. '%s*(%S+)')
 			if match then
 				ver = match
 				break
@@ -72,109 +57,204 @@ function datfile.open(file, vertag, fixupcb)
 		end
 	end
 	if not ver then
-		-- use file ctime for version
-		ver = tostring(lfs.attributes(filepath, "change"))
+		-- fall back to file modification time for version
+		ver = tostring(lfs.attributes(filepath, 'change'))
 	end
 	if ver == dbver then
 		fh:close()
-		return readret(file), dbver
+		return readret(file, tablename), dbver
 	end
 
-	if dbver then
-		db.exec("DELETE FROM \"" .. file .. "\"")
-		db.check("deleting")
-		db.exec("DELETE FROM \"" .. file .. "_idx\"")
-		db.check("deleting index")
-		stmt = db.prepare("UPDATE version SET version = ? WHERE datfile = ?")
-		db.check("updating version")
-	else
-		stmt = db.prepare("INSERT INTO version VALUES (?, ?)")
-		db.check("inserting version")
+	if not dbver then
+		db.exec(
+			string.format(
+				[[CREATE TABLE "%s_idx" (
+					type VARCHAR NOT NULL,
+					val VARCHAR NOT NULL,
+					romset VARCHAR NOT NULL,
+					data INTEGER NOT NULL);]],
+				tablename))
+		db.check(string.format('creating %s index table', file))
+		db.exec(string.format([[CREATE TABLE "%s" (data CLOB NOT NULL);]], tablename))
+		db.check(string.format('creating %s data table', file))
+		db.exec(
+			string.format(
+				[[CREATE INDEX "typeval_%s" ON "%s_idx" (type, val, romset);]],
+				tablename, tablename))
+		db.check(string.format('creating %s type/value index', file))
 	end
-	stmt:bind_values(ver, file)
-	stmt:step()
-	stmt:finalize()
 
-	do
-		fh:seek("set")
-		local buffer = fh:read("a")
-		db.exec("BEGIN TRANSACTION")
-		db.check("beginning transaction")
-		local function gmatchpos()
-			local pos = 1
-			local function iter()
-				local tags, data
-				while not data do
-					local npos
-					local spos, epos = buffer:find("[\n\r]$[^=\n\r]*=[^\n\r]*", pos)
-					if not spos then
-						return nil
-					end
-					npos, epos = buffer:find("[\n\r]$%w+%s*[\n\r]+", epos)
-					if not npos then
-						return nil
-					end
-					tags = buffer:sub(spos, epos)
-					spos, npos = buffer:find("[\n\r]$[^=\n\r]*=[^\n\r]*", epos)
-					if not spos then
-						return nil
-					end
-					data = buffer:sub(epos, spos)
-					pos = spos
-				end
-				return tags, data
-			end
-			return iter
+	db.exec([[BEGIN TRANSACTION;]])
+	if not db.check(string.format('starting %s transaction', file)) then
+		fh:close()
+		if dbver then
+			return readret(file, tablename), dbver
+		else
+			return nil
 		end
-		for info, data in gmatchpos() do
-			local tags = {}
-			local infotype
-			info = info:gsub(utf8.char(0xfeff), "") --remove boms
-			data = data:gsub(utf8.char(0xfeff), "")
-			for s in info:gmatch("[\n\r]$([^\n\r]*)") do
-				if s:find("=", 1, true) then
-					local m1, m2 = s:match("([^=]*)=(.*)")
-					for tag in m1:gmatch("[^,]+") do
-						for set in m2:gmatch("[^,]+") do
-							tags[#tags + 1] = { tag = tag, set = set }
-						end
+	end
+
+	-- clean out previous data and update the version
+	if dbver then
+		db.exec(string.format([[DELETE FROM "%s";]], tablename))
+		if not db.check(string.format('deleting previous %s data', file)) then
+			db.exec([[ROLLBACK TRANSACTION;]])
+			fh:close()
+			return readret(file, tablename), dbver
+		end
+		db.exec(string.format([[DELETE FROM "%s_idx";]], tablename))
+		if not db.check(string.format('deleting previous %s data', file)) then
+			db.exec([[ROLLBACK TRANSACTION;]])
+			fh:close()
+			return readret(file, tablename), dbver
+		end
+	end
+	db.set_version(file, ver)
+	if not db.check(string.format('updating %s version', file)) then
+		db.exec([[ROLLBACK TRANSACTION;]])
+		fh:close()
+		if dbver then
+			return readret(file, tablename), dbver
+		else
+			return nil
+		end
+	end
+
+	local dataquery = db.prepare(
+		string.format([[INSERT INTO "%s" (data) VALUES (?);]], tablename))
+	local indexquery = db.prepare(
+		string.format(
+			[[INSERT INTO "%s_idx" (type, val, romset, data) VALUES (?, ?, ?, ?)]],
+			tablename))
+
+	fh:seek('set')
+	local buffer = fh:read('a')
+
+	local function gmatchpos()
+		local pos = 1
+		local function iter()
+			local tags, data
+			while not data do
+				local npos
+				local spos, epos = buffer:find('[\n\r]$[^=\n\r]*=[^\n\r]*', pos)
+				if not spos then
+					return nil
+				end
+				npos, epos = buffer:find('[\n\r]$%w+%s*[\n\r]+', epos)
+				if not npos then
+					return nil
+				end
+				tags = buffer:sub(spos, epos)
+				spos, npos = buffer:find('[\n\r]$[^=\n\r]*=[^\n\r]*', epos)
+				if not spos then
+					return nil
+				end
+				data = buffer:sub(epos, spos)
+				pos = spos
+			end
+			return tags, data
+		end
+		return iter
+	end
+
+	for info, data in gmatchpos() do
+		local tags = {}
+		local infotype
+		info = info:gsub(utf8.char(0xfeff), '') -- remove byte order marks
+		data = data:gsub(utf8.char(0xfeff), '')
+		for s in info:gmatch('[\n\r]$([^\n\r]*)') do
+			if s:find('=', 1, true) then
+				local m1, m2 = s:match('([^=]*)=(.*)')
+				for tag in m1:gmatch('[^,]+') do
+					for set in m2:gmatch('[^,]+') do
+						table.insert(tags, { tag = tag, set = set })
 					end
-				else
-					infotype = s
+				end
+			else
+				infotype = s
+				break
+			end
+		end
+
+		data = data:gsub('[\n\r]$end%s*[\n\r]$%w+%s*[\n\r]', '\n')
+		data = data:gsub('[\n\r]$end%s*[\n\r].-[\n\r]$%w+%s*[\n\r]', '\n')
+		data = data:gsub('[\n\r]$end%s*[\n\r].*', '')
+
+		if (#tags > 0) and infotype then
+			data = data:gsub('\r', '') -- strip carriage returns
+			if fixupcb then
+				data = fixupcb(data)
+			end
+
+			dataquery:bind_values(data)
+			local row
+			while true do
+				local status = dataquery:step()
+				if status == db.DONE then
+					row = dataquery:last_insert_rowid();
+					break
+				elseif status == db.BUSY then
+					emu.print_error(string.format('Database busy: inserting %s data', file))
+					dataquery:finalize()
+					indexquery:finalize()
+					db.exec([[ROLLBACK TRANSACTION;]])
+					fh:close()
+					if dbver then
+						return readret(file, tablename), dbver
+					else
+						return nil
+					end
+				elseif result ~= db.ROW then
+					db.check(string.format('inserting %s data', file))
 					break
 				end
 			end
+			dataquery:reset()
 
-			data = data:gsub("[\n\r]$end%s*[\n\r]$%w+%s*[\n\r]", "\n")
-			data = data:gsub("[\n\r]$end%s*[\n\r].-[\n\r]$%w+%s*[\n\r]", "\n")
-			data = data:gsub("[\n\r]$end%s*[\n\r].*", "")
-
-			if #tags > 0 and infotype then
-				data = data:gsub("\r", "") -- strip crs
-				if fixupcb then
-					data = fixupcb(data)
-				end
-				stmt = db.prepare("INSERT INTO \"" .. file .. "\" VALUES (?)")
-				db.check("inserting values")
-				stmt:bind_values(data)
-				stmt:step()
-				local row = stmt:last_insert_rowid()
-				stmt:finalize()
+			if row then
 				for num, tag in pairs(tags) do
-					stmt = db.prepare("INSERT INTO \"" .. file .. "_idx\" VALUES (?, ?, ?, ?)")
-					db.check("inserting into index")
-					stmt:bind_values(infotype, tag.tag, tag.set, row)
-					stmt:step()
-					stmt:finalize()
+					indexquery:bind_values(infotype, tag.tag, tag.set, row)
+					while true do
+						local status = indexquery:step()
+						if status == db.DONE then
+							break
+						elseif status == db.BUSY then
+							emu.print_error(string.format('Database busy: inserting %s data', file))
+							dataquery:finalize()
+							indexquery:finalize()
+							db.exec([[ROLLBACK TRANSACTION;]])
+							fh:close()
+							if dbver then
+								return readret(file, tablename), dbver
+							else
+								return nil
+							end
+						elseif result ~= db.ROW then
+							db.check(string.format('inserting %s data', file))
+							break
+						end
+					end
+					indexquery:reset()
 				end
 			end
 		end
-		db.exec("END TRANSACTION")
-		db.check("ending transaction")
 	end
-	fh:close()
 
-	return readret(file), ver
+	dataquery:finalize()
+	indexquery:finalize()
+
+	fh:close()
+	db.exec([[COMMIT TRANSACTION;]])
+	if not db.check(string.format('committing %s transaction', file)) then
+		db.exec([[ROLLBACK TRANSACTION;]])
+		if dbver then
+			return readret(file, tablename), dbver
+		else
+			return nil
+		end
+	end
+
+	return readret(file, tablename), ver
 end
 
 return datfile
diff --git a/src/devices/bus/nubus/nubus_48gc.cpp b/src/devices/bus/nubus/nubus_48gc.cpp
index 899910b52c6..506e6857248 100644
--- a/src/devices/bus/nubus/nubus_48gc.cpp
+++ b/src/devices/bus/nubus/nubus_48gc.cpp
@@ -8,10 +8,8 @@
 
   TODO:
   * Work out why some monitors need magic multiply or divide by two to
-    get the right RAMDAC clock - inferring it from the reference clock
-    modulus is definitely wrong.
-  * When a monochrome monitor is connected, it sends the intensity to the
-    blue channel - maybe detect this and map blue channel to white?
+    get the right RAMDAC/CRTC clocks - inferring it from the reference
+    clock modulus is definitely wrong.
   * The 8•24 card uses a strange off-white palette with some monitors,
     including the 21" and 16" RGB displays.
   * Interlaced modes.
@@ -38,7 +36,7 @@
 
 static INPUT_PORTS_START( 48gc )
 	PORT_START("MONITOR")
-	PORT_CONFNAME(0x07, 0x06, u8"Attached monitor")
+	PORT_CONFNAME(0x0f, 0x06, u8"Attached monitor")
 	PORT_CONFSETTING(   0x00, u8"Macintosh Two-Page Monitor (1152\u00d7870)")
 	PORT_CONFSETTING(   0x01, u8"Macintosh Portrait Display (B&W 15\" 640\u00d7870)")
 	PORT_CONFSETTING(   0x02, u8"Macintosh RGB Display (12\" 512\u00d7384)")
@@ -51,14 +49,14 @@ INPUT_PORTS_END
 
 static INPUT_PORTS_START( 824gc )
 	PORT_START("MONITOR")
-	PORT_CONFNAME(0x07, 0x06, u8"Attached monitor")
+	PORT_CONFNAME(0x0f, 0x06, u8"Attached monitor")
 	PORT_CONFSETTING(   0x00, u8"Mac 21\" Color Display (1152\u00d7870)")
 	PORT_CONFSETTING(   0x01, u8"Mac Portrait Display (B&W 15\" 640\u00d7870)")
 	PORT_CONFSETTING(   0x02, u8"Mac RGB Display (12\" 512\u00d7384)")
 	PORT_CONFSETTING(   0x03, u8"Mac Two-Page Display (B&W 21\" 1152\u00d7870)")
 	//PORT_CONFSETTING(   0x04, u8"NTSC Monitor") requires implementing interlace modes
-	PORT_CONFSETTING(   0x05, u8"Mac 16\" Color Display (832\u00d7624)")
 	PORT_CONFSETTING(   0x06, u8"Mac Hi-Res Display (12-14\" 640\u00d7480)")
+	PORT_CONFSETTING(   0x0d, u8"Mac 16\" Color Display (832\u00d7624)")
 INPUT_PORTS_END
 
 
@@ -80,6 +78,27 @@ DEFINE_DEVICE_TYPE(NUBUS_48GC,  nubus_48gc_device,  "nb_48gc",  "Apple Macintosh
 DEFINE_DEVICE_TYPE(NUBUS_824GC, nubus_824gc_device, "nb_824gc", "Apple Macintosh Display Card 8*24")
 
 
+// TODO: find a better place for this table to live
+struct mac_monitor_info { bool mono; unsigned sense[4]; };
+static mac_monitor_info const f_monitors[] = {
+	{ false, { 0, 0, 0, 0 } },      //  0: RGB 21"
+	{ true,  { 1, 1, 1, 0 } },      //  1: Full-Page (B&W 15")
+	{ false, { 2, 2, 0, 2 } },      //  2: RGB 12"
+	{ true,  { 3, 3, 1, 2 } },      //  3: Two-Page (B&W 21")
+	{ false, { 4, 0, 4, 4 } },      //  4: NTSC Monitor
+	{ false, { 5, 1, 5, 4 } },      //  5: RGB 15"
+	{ false, { 6, 2, 4, 6 } },      //  6: Hi-Res (12-14")
+	{ false, { 6, 0, 0, 6 } },      //  7: Multiple Scan 14"
+	{ false, { 6, 0, 4, 6 } },      //  8: Multiple Scan 16"
+	{ false, { 6, 2, 0, 6 } },      //  9: Multiple Scan 21"
+	{ false, { 7, 0, 0, 0 } },      // 10: PAL Encoder
+	{ false, { 7, 1, 1, 0 } },      // 11: NTSC Encoder
+	{ false, { 7, 1, 1, 6 } },      // 12: VGA/Super VGA
+	{ false, { 7, 2, 5, 2 } },      // 13: RGB 16"
+	{ false, { 7, 3, 0, 0 } },      // 14: PAL Monitor
+	{ false, { 7, 3, 4, 4 } } };    // 15: RGB 19"
+
+
 //-------------------------------------------------
 //  device_add_mconfig - add device configuration
 //-------------------------------------------------
@@ -149,7 +168,7 @@ jmfb_device::jmfb_device(const machine_config &mconfig, device_type type, const
 	m_monitor(*this, "MONITOR"),
 	m_vram_view(*this, "vram"),
 	m_timer(nullptr),
-	m_vbl_disable(0), m_toggle(0), m_stride(0), m_base(0),
+	m_vbl_disable(0), m_toggle(0),
 	m_count(0), m_clutoffs(0), m_mode(0)
 {
 	set_screen(*this, GC48_SCREEN_NAME);
@@ -191,13 +210,18 @@ void jmfb_device::device_start()
 
 	m_timer = timer_alloc(FUNC(jmfb_device::vbl_tick), this);
 
+	m_monitor_type = 0;
+	m_mode = 0;
+
+	save_item(NAME(m_monitor_type));
 	save_item(NAME(m_vram));
 	save_item(NAME(m_vbl_disable));
 	save_item(NAME(m_toggle));
-	save_item(NAME(m_stride));
-	save_item(NAME(m_base));
 	save_item(NAME(m_registers));
+	save_item(NAME(m_sense));
 	save_item(NAME(m_preload));
+	save_item(NAME(m_base));
+	save_item(NAME(m_stride));
 	save_item(NAME(m_colors));
 	save_item(NAME(m_count));
 	save_item(NAME(m_clutoffs));
@@ -243,12 +267,19 @@ void jmfb_device::device_reset()
 {
 	m_vram_view.select(0);
 
+	m_monitor_type = m_monitor->read();
+	if (m_monitor_type > std::size(f_monitors))
+	{
+		throw emu_fatalerror("%s: Invalid monitor selection %x\n", m_monitor_type);
+	}
+
 	std::fill(m_vram.begin(), m_vram.end(), 0);
 	m_vbl_disable = 1;
 	m_toggle = 0;
-	m_stride = 80 / 4;
-	m_base = 0;
+	m_sense = 0;
 	m_preload = 256 - 8;
+	m_base = 0;
+	m_stride = 80 / 4;
 
 	m_clutoffs = 0;
 	m_count = 0;
@@ -287,6 +318,11 @@ TIMER_CALLBACK_MEMBER(jmfb_device::vbl_tick)
 
 uint32_t jmfb_device::screen_update(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect)
 {
+	auto const trans =
+		[mono = f_monitors[m_monitor_type].mono] (rgb_t color)
+		{
+			return !mono ? color : rgb_t(color.b(), color.b(), color.b());
+		};
 	auto const screenbase = util::big_endian_cast<uint8_t const>(&m_vram[0]) + (m_base << 5);
 	int const xres = screen.visible_area().right();
 
@@ -301,14 +337,14 @@ uint32_t jmfb_device::screen_update(screen_device &screen, bitmap_rgb32 &bitmap,
 				{
 					uint8_t const pixels = rowbase[x];
 
-					*scanline++ = pen_color(BIT(pixels, 7));
-					*scanline++ = pen_color(BIT(pixels, 6));
-					*scanline++ = pen_color(BIT(pixels, 5));
-					*scanline++ = pen_color(BIT(pixels, 4));
-					*scanline++ = pen_color(BIT(pixels, 3));
-					*scanline++ = pen_color(BIT(pixels, 2));
-					*scanline++ = pen_color(BIT(pixels, 1));
-					*scanline++ = pen_color(BIT(pixels, 0));
+					*scanline++ = trans(pen_color(BIT(pixels, 7)));
+					*scanline++ = trans(pen_color(BIT(pixels, 6)));
+					*scanline++ = trans(pen_color(BIT(pixels, 5)));
+					*scanline++ = trans(pen_color(BIT(pixels, 4)));
+					*scanline++ = trans(pen_color(BIT(pixels, 3)));
+					*scanline++ = trans(pen_color(BIT(pixels, 2)));
+					*scanline++ = trans(pen_color(BIT(pixels, 1)));
+					*scanline++ = trans(pen_color(BIT(pixels, 0)));
 				}
 			}
 			break;
@@ -322,10 +358,10 @@ uint32_t jmfb_device::screen_update(screen_device &screen, bitmap_rgb32 &bitmap,
 				{
 					uint8_t const pixels = rowbase[x];
 
-					*scanline++ = pen_color(BIT(pixels, 6, 2));
-					*scanline++ = pen_color(BIT(pixels, 4, 2));
-					*scanline++ = pen_color(BIT(pixels, 2, 2));
-					*scanline++ = pen_color(BIT(pixels, 0, 2));
+					*scanline++ = trans(pen_color(BIT(pixels, 6, 2)));
+					*scanline++ = trans(pen_color(BIT(pixels, 4, 2)));
+					*scanline++ = trans(pen_color(BIT(pixels, 2, 2)));
+					*scanline++ = trans(pen_color(BIT(pixels, 0, 2)));
 				}
 			}
 			break;
@@ -339,8 +375,8 @@ uint32_t jmfb_device::screen_update(screen_device &screen, bitmap_rgb32 &bitmap,
 				{
 					uint8_t const pixels = rowbase[x];
 
-					*scanline++ = pen_color(BIT(pixels, 4, 4));
-					*scanline++ = pen_color(BIT(pixels, 0, 4));
+					*scanline++ = trans(pen_color(BIT(pixels, 4, 4)));
+					*scanline++ = trans(pen_color(BIT(pixels, 0, 4)));
 				}
 			}
 			break;
@@ -352,7 +388,7 @@ uint32_t jmfb_device::screen_update(screen_device &screen, bitmap_rgb32 &bitmap,
 				uint32_t *scanline = &bitmap.pix(y);
 				for (int x = 0; x <= xres; x++)
 				{
-					*scanline++ = pen_color(rowbase[x]);
+					*scanline++ = trans(pen_color(rowbase[x]));
 				}
 			}
 			break;
@@ -364,7 +400,10 @@ uint32_t jmfb_device::screen_update(screen_device &screen, bitmap_rgb32 &bitmap,
 				uint32_t *scanline = &bitmap.pix(y);
 				for (int x = 0; x <= xres; x++)
 				{
-					*scanline++ = rgb_t(source[0], source[1], source[2]);
+					if (!f_monitors[m_monitor_type].mono)
+						*scanline++ = rgb_t(source[0], source[1], source[2]);
+					else
+						*scanline++ = rgb_t(source[2], source[2], source[2]);
 					source += 3;
 				}
 			}
@@ -378,8 +417,20 @@ void jmfb_device::update_crtc()
 {
 	int const vtotal = (m_vactive + m_vbporch + m_vsync + m_vfporch) / 2;
 	int const height = m_vactive / 2;
-	if (vtotal && height && m_multiplier)
+	if (vtotal && height && m_multiplier && m_modulus)
 	{
+		int const divider = 256 - m_preload;
+		XTAL const refclk = 20_MHz_XTAL / m_modulus;
+		XTAL const vcoout = refclk * m_multiplier;
+		XTAL const pixclk = vcoout / (1 << m_pdiv);
+		XTAL const dacclk = pixclk / divider;
+		LOG("reference clock %d VCO output %d pixel clock %d RAMDAC clock %d\n",
+				refclk.value(), vcoout.value(), pixclk.value(), dacclk.value());
+
+		int htotal = m_hactive + m_hbporch + m_hsync + m_hfporch + 8;
+		int width = m_hactive + 2;
+		LOG("horizontal total %d active %d\n", htotal, width);
+
 		// FIXME: where does this multiply/divide by 2 come from?
 		// This is obviously not correct by any definition.
 		int scale = 0;
@@ -398,9 +449,8 @@ void jmfb_device::update_crtc()
 		default:
 			throw emu_fatalerror("%s: Unknown clock modulus %d\n", tag(), m_modulus);
 		}
-		int const divider = 256 - unsigned(m_preload);
-		int htotal = ((m_hactive + m_hbporch + m_hsync + m_hfporch + 8) << (m_pdiv + scale)) / divider;
-		int width = ((m_hactive + 2) << (m_pdiv + scale)) / divider;
+		htotal = ((m_hactive + m_hbporch + m_hsync + m_hfporch + 8) << (m_pdiv + scale)) / divider;
+		width = ((m_hactive + 2) << (m_pdiv + scale)) / divider;
 		switch (m_mode)
 		{
 			case 0: // 1bpp:
@@ -440,7 +490,16 @@ uint32_t jmfb_device::jmfb_r(offs_t offset, uint32_t mem_mask)
 	switch (offset)
 	{
 		case 0x000/4:
-			return m_monitor->read() << 9;
+			{
+				uint32_t result = f_monitors[m_monitor_type].sense[0];
+				if (BIT(m_sense, 2))
+					result &= f_monitors[m_monitor_type].sense[1];
+				if (BIT(m_sense, 1))
+					result &= f_monitors[m_monitor_type].sense[2];
+				if (BIT(m_sense, 0))
+					result &= f_monitors[m_monitor_type].sense[3];
+				return result << 9;
+			}
 
 		case 0x1c0/4:
 			m_toggle ^= 0xffffffff;
@@ -462,23 +521,24 @@ void jmfb_device::jmfb_w(offs_t offset, uint32_t data, uint32_t mem_mask)
 			{
 				m_vram_view.select(BIT(data, 2)); // packed RGB mode
 			}
+			m_sense = (data >> 9) & 0x07;
 			break;
 
 		case 0x004/4:
 			LOG("%s: %02x to preload\n", machine().describe_context(), data);
-			m_preload = data;
+			m_preload = data & 0xff;
 			update_crtc();
 			break;
 
 		case 0x008/4: // base
 			LOG("%s: %x to base\n", machine().describe_context(), data);
-			m_base = data;
+			m_base = data & 0xffff;
 			break;
 
 		case 0x00c/4: // stride
 			LOG("%s: %x to stride\n", machine().describe_context(), data);
 			// this value is in DWORDs for 1-8 bpp and, uhh, strange for 24bpp
-			m_stride = data;
+			m_stride = data & 0xffff;
 			break;
 
 		case 0x10c/4: // active pixel cells - 2
diff --git a/src/devices/bus/nubus/nubus_48gc.h b/src/devices/bus/nubus/nubus_48gc.h
index d0b433bf1a6..50abdc9f679 100644
--- a/src/devices/bus/nubus/nubus_48gc.h
+++ b/src/devices/bus/nubus/nubus_48gc.h
@@ -53,10 +53,14 @@ private:
 	memory_view m_vram_view;
 	emu_timer *m_timer;
 
+	uint8_t m_monitor_type;
+
 	std::vector<uint32_t> m_vram;
-	uint32_t m_vbl_disable, m_toggle, m_stride, m_base;
+	uint32_t m_vbl_disable, m_toggle;
 	uint32_t m_registers[0x100];
-	uint8_t m_preload;
+	uint8_t m_sense;
+	uint16_t m_preload;
+	uint32_t m_base, m_stride;
 
 	uint8_t m_colors[3], m_count, m_clutoffs, m_mode;
 
diff --git a/src/devices/bus/nubus/nubus_specpdq.cpp b/src/devices/bus/nubus/nubus_specpdq.cpp
index 62c1aec9e29..33a3c5a3e42 100644
--- a/src/devices/bus/nubus/nubus_specpdq.cpp
+++ b/src/devices/bus/nubus/nubus_specpdq.cpp
@@ -10,7 +10,7 @@
 
   06 = ?
   07 = command - 002 = pattern fill, 100/101 = copy forward/backward
-  08 = pattern offset - X in bits 0-2, Y in bits 3-6
+  08 = pattern Y offset * 8
   09 = VRAM destination * 4
   0a = VRAM source * 4
   0b = height (inclusive)