diff --git a/build.lua b/build.lua
index af4623f..8019e8e 100644
--- a/build.lua
+++ b/build.lua
@@ -190,18 +190,32 @@ local function buildKernel(dst)
 end
 
 fs.makeDirectory(outdir)
+
+--boot eeprom
 exportFile('boot.lua')
 
+--[=====[ core: a minimal system to build off of ]=====]--
 fs.makeDirectory(outdir .. 'core/')
 buildKernel('core/init.lua')
-
+-- core bin/
 fs.makeDirectory(outdir .. 'core/bin')
-exportFile('bin/tty.lua', 'core/')
+exportFile('bin/lua.lua', 'core/')
+exportFile('bin/multitty.lua', 'core/')
+-- core lib/
+fs.makeDirectory(outdir .. 'core/lib')
+exportFile('lib/term.lua', 'core/')
 
+--[=====[ livedisk: a self-contained bootable system for an introduction to kitn ]=====]--
 fs.makeDirectory(outdir .. 'livedisk/')
 assert(fs.copy(outdir .. 'core/init.lua', outdir .. 'livedisk/init.lua'))
+-- livedisk bin/
 fs.makeDirectory(outdir .. 'livedisk/bin/')
-assert(fs.copy(outdir .. 'core/bin/tty.lua', outdir .. 'livedisk/bin/tty.lua'))
+assert(fs.copy(outdir .. 'core/bin/lua.lua', outdir .. 'livedisk/bin/lua.lua'))
+assert(fs.copy(outdir .. 'core/bin/multitty.lua', outdir .. 'livedisk/bin/multitty.lua'))
+-- livedisk lib/
+fs.makeDirectory(outdir .. 'livedisk/lib/')
+assert(fs.copy(outdir .. 'core/lib/term.lua', outdir .. 'livedisk/lib/term.lua'))
+-- livedisk etc/
 fs.makeDirectory(outdir .. 'livedisk/etc/')
 exportFile('livedisk/init.lua', 'livedisk/etc/init.lua')
 
diff --git a/src/bin/lua.lua b/src/bin/lua.lua
new file mode 100644
index 0000000..0276c68
--- /dev/null
+++ b/src/bin/lua.lua
@@ -0,0 +1,55 @@
+local ok, err = xpcall(function(...)
+local tty = ...
+io.stdin, io.stdout = tty, tty
+local term = dofile('/lib/term.lua').wrap(io) --TODO require()
+
+term:write(_VERSION, ' // ', _OSVERSION, '\n')
+
+local env = setmetatable({}, {__index = _ENV}) --TODO pcall require() on __index
+
+::repl::
+local line, err = term:prompt({ fg = 0x00ff00, 'lua> ' })
+if not line then
+	if err == nil then --eof
+		return
+	elseif err == 'interrupted' then
+		term:write('\n')
+		goto repl
+	else
+		error(err)
+	end
+end
+
+local f, err = load('return ' .. line, '=expr', 't', env)
+if not f then f, err = load(line, '=repl', 't', env) end
+if not f then
+	term:error(tostring(err), '\n')
+	goto repl
+end
+
+local results = table.pack(pcall(f))
+if not results[1] then
+	term:error('error: ', tostring(results[2]), '\n')
+	goto repl
+end
+
+for i = 2, results.n do
+	local val = results[i]
+	local t = type(val)
+	if i > 2 then term:write('\t') end
+	if t == 'nil' or t == 'boolean' or t == 'number' then
+		term:write({ fg = 0xffff00, tostring(val) })
+	elseif t == 'string' then
+		term:write({ fg = 0x9292ff, string.format('%q', val) })
+	else
+		term:write({ fg = 0xff80ff, tostring(val) })
+	end
+end
+
+if results.n > 1 then term:write('\n') end
+
+goto repl
+end, function(e) return debug.traceback(tostring(e)) end, ...)
+if not ok then error(err, 0) end
+
+-- vi: set ts=2:
diff --git a/src/bin/multitty.lua b/src/bin/multitty.lua
new file mode 100644
index 0000000..cbf8fe6
--- /dev/null
+++ b/src/bin/multitty.lua
@@ -0,0 +1,176 @@
+--provide a tty on each available screen, running the given program
+local progArgs = table.pack(...)
+checkArg(1, progArgs[1], 'string') --program path
+
+
+--identify the highest-tier gpu available
+local gpu, vmem --use virtual memory as a heuristic for tier
+for addr in component.list('gpu', true) do
+	local vmemNew = component.invoke(addr, 'totalMemory')
+	if vmemNew > (vmem or -1) then
+		gpu, vmem = addr, vmemNew
+	end
+end
+gpu = assert(gpu, 'please install a GPU or APU to continue')
+
+--track most recently assigned values to skip redundant bind/setBackground/setForeground calls
+local curScreen, curBg, curFg
+local function bind(screen)
+	if screen ~= curScreen then
+		component.invoke(gpu, 'bind', screen)
+		curScreen = screen
+	end
+end
+local function setBackground(color)
+	if color ~= curBg then
+		component.invoke(gpu, 'setBackground', color)
+		curBg = color
+	end
+end
+local function setForeground(color)
+	if color ~= curFg then
+		component.invoke(gpu, 'setForeground', color)
+		curFg = color
+	end
+end
+local function draw(cx, text)
+	bind(cx.screen)
+	setBackground(cx.bg)
+	setForeground(cx.fg)
+	return component.invoke(gpu, 'set', cx.x, cx.y, text)
+end
+
+local iomt = {}
+iomt.__index = iomt
+
+local function isAttachedKeyboard(cx, addr)
+	for i, kb in ipairs(cx.keyboards) do
+		if kb == addr then
+			return i
+		end
+	end
+end
+
+--tail-recursively pullSignal to construct the line of input read from a terminal
+local function readSignal(cx, input, sig, ...)
+	if sig == 'key_down' then
+		local kb, ch, code = ...
+		if isAttachedKeyboard(cx, kb) then
+			if code == 28 then --enter
+				cx.x, cx.y = 1, cx.y + 1
+				return input .. '\n'
+			elseif code == 14 then --backspace
+				if input ~= '' then
+					cx.x = cx.x - 1
+					draw(cx, ' ')
+					input = input:sub(1, -2)
+				end
+			elseif ch ~= 0 then
+				local char = string.char(ch)
+				draw(cx, char)
+				cx.x = cx.x + 1
+				input = input .. char
+			end
+		end
+	elseif sig == 'component_added' then
+		local addr, ty = ...
+		if ty == 'keyboard' then
+			cx.keyboards = component.invoke(screen, 'getKeyboards')
+		end
+	elseif sig == 'component_removed' then
+		local addr, ty = ...
+		if addr == cx.screen then
+			return nil, 'disconnected'
+		end
+		local idx = ty == 'keyboard' and isAttachedKeyboard(cx, addr)
+		if idx then
+			table.remove(cx.keyboards, idx)
+		end
+	end
+
+	return readSignal(cx, input, computer.pullSignal())
+end
+
+-- file handle methods
+function iomt:read(n)
+	--technically this should return at maximum `n` bytes, but that would involve a redundant second buffer
+	--we happen to know the implementation works fine returning more than `n`
+
+	return readSignal(self, '', computer.pullSignal())
+	--[[
+	local sig = table.pack(computer.pullSignal())
+	for i = 1, sig.n do
+		sig[i] = string.format(type(sig[i]) == 'string' and '%q' or '%s', sig[i])
+	end
+	return table.concat(sig, ', ', 1, sig.n) .. '\n'
+	]]
+end
+
+function iomt:write(data)
+	bind(self.screen) setBackground(self.bg) setForeground(self.fg)
+	local idx = 1
+	::line::
+	local lf = data:find('\n', idx, true)
+	component.invoke(gpu, 'set', self.x, self.y, data:sub(idx, lf and lf - 1))
+
+	if lf then
+		self.x, self.y = 1, self.y + 1
+		idx = lf + 1
+		goto line
+	end
+
+	self.x = self.x + #data - idx + 1
+	return true
+end
+
+--no seek, noop close
+function iomt:close() return true end
+
+-- tty methods
+function iomt:mark()
+	return { bg = self.bg, fg = self.fg }
+end
+function iomt:reset(mark)
+	self.bg, self.fg = mark.bg, mark.fg
+end
+function iomt:setBg(color) self.bg = color end
+function iomt:setFg(color) self.fg = color end
+
+
+local function createTerm(screen, prog, ...)
+	checkArg(1, screen, 'string')
+	checkArg(2, prog, 'string')
+	local fh = setmetatable({ screen = screen, keyboards = component.invoke(screen, 'getKeyboards'), x = 1, y = 1, fg = 0xffffff, bg = 0x000000 }, iomt)
+	local stdio = assert(kitn.wrapFile('r+', fh))
+	stdio.tty = fh
+
+	bind(screen)
+	setForeground(0xffffff)
+	setBackground(0x000000)
+	local w, h = component.invoke(gpu, 'maxResolution')
+	component.invoke(gpu, 'setResolution', w, h)
+	component.invoke(gpu, 'fill', 1, 1, w, h, ' ')
+
+	local process = assert(kitn.createProcess(prog, stdio, ...)) --TODO set io via createProcess args
+	return process, stdio
+end
+
+
+
+--for each existing screen, spawn prog
+for screen in component.list('screen') do
+	createTerm(screen, table.unpack(progArgs, 1, progArgs.n))
+end
+
+--when new screens are added, spawn prog on those too
+local function tick(sig, addr, ty)
+	if sig == 'component_added' and ty == 'screen' then
+		createTerm(addr, table.unpack(progArgs, 1, progArgs.n))
+	end
+
+	return tick(computer.pullSignal())
+end
+
+return tick(computer.pullSignal())
+
+-- vi: set ts=2:
diff --git a/src/kernel/02_io.lua b/src/kernel/02_io.lua
index e8b4c35..6d2bdf7 100644
--- a/src/kernel/02_io.lua
+++ b/src/kernel/02_io.lua
@@ -1,4 +1,4 @@
-local openNull, openPath
+local openNull, openPath, wrapFile
 do
 	local filedata = setmetatable({}, { __mode = 'k' }) --weak-keyed mapping of file object to data/inner (fh of wrapFile)
 	local filemt = { __metatable = '<file>' }
@@ -13,7 +13,7 @@ do
 		end
 	end
 
-	local function wrapFile(mode, fh)
+	function wrapFile(mode, fh)
 		local rwa, b, plus, b2 = match(mode or 'r', '^([rwa])(b?)(%+?)(b?)$') --match all of x, xb, x+, xb+, x+b
 		if not rwa or (b ~= '' and b2 ~= '') then return nil, 'bad mode' end
 
@@ -123,6 +123,31 @@ do
 				fh._file_rbuf = ''
 				return cat
 			end
+		elseif n == 'l' then
+			local lf1, lf2 = fh._file_rbuf:find('\n')
+			if lf1 then
+				local line = fh._file_rbuf:sub(1, lf1 - 1)
+				fh._file_rbuf = fh._file_rbuf:sub(lf2 + 1)
+				return line
+			end
+
+			::read::
+
+			local parts = { fh._file_rbuf }
+			local chunk, err = fh:read(512) --TODO tune default capacity to e.g. free memory
+			if not chunk then
+				fh._file_rbuf = concat(parts)
+				return nil, err
+			end
+
+			parts[#parts+1] = chunk
+
+			lf1, lf2 = chunk:find('\n')
+			if not lf1 then goto read end
+
+			fh._file_rbuf = chunk:sub(lf2 + 1)
+			parts[#parts] = chunk:sub(1, lf1 - 1)
+			return concat(parts)
 		else
 			error('TODO read1 patterns')
 		end
diff --git a/src/kernel/04_environment.lua b/src/kernel/04_environment.lua
index 75f472d..c814fd7 100644
--- a/src/kernel/04_environment.lua
+++ b/src/kernel/04_environment.lua
@@ -9,7 +9,7 @@ given <https://ocdoc.cil.li/tutorial:custom_oses#what_s_available>:
 ]]
 
 
-envBase._OSVERSION = 'kitn 0.2.0-beta.3' --prefer [openloader, openos] "$name $ver" over plan9k "$name/$ver"
+envBase._OSVERSION = 'kitn 0.2.0-beta.4' --prefer [openloader, openos] "$name $ver" over plan9k "$name/$ver"
 envBase.kitn = {}
 envBase._G, envBase.load = nil
 
@@ -184,6 +184,20 @@ function fillEnv(proc, uenv)
 		end
 		return openPath(mode, address, path)
 	end
+
+	local function wrap_read(fh, ...) return fh.stream:read(...) end
+	local function wrap_write(fh, ...) return fh.stream:write(...) end
+	local function wrap_seek(fh, ...) return fh.stream:seek(...) end
+	local function wrap_close(fh, ...) return fh.stream:close(...) end
+
+	--TODO expose this as a require()able library like <https://ocdoc.cil.li/api:buffer>
+	function ukitn.wrapFile(mode, stream)
+		checkArg(1, mode, 'string')
+		checkArg(2, stream, 'table')
+		--in the kernel, we can take a shortcut and add _file_* attributes directly to the caller's (our own) fh. we don't
+		--want to do that to arbitrary userspace values though, so we add another layer of indirection.
+		return wrapFile(mode, { stream = stream, read = wrap_read, write = wrap_write, seek = wrap_seek, close = wrap_close })
+	end
 end
 
 -- vi: set ts=2:
diff --git a/src/lib/term.lua b/src/lib/term.lua
new file mode 100644
index 0000000..254ea3c
--- /dev/null
+++ b/src/lib/term.lua
@@ -0,0 +1,89 @@
+local mt = {}
+mt.__index = mt
+
+--wrap the current process's stdio streams into a tty that supports styled output.
+local function wrap(io_)
+	checkArg(1, io_, 'table', 'nil')
+	io_ = io_ or io
+
+	--cache the streams here so that `local tty = wrap(io); io.output('/some/file'); tty.prompt()` works as expected
+	local stdin, stdout, stderr = io_.stdin, io_.stdout, io_.stderr
+	if stdout.tty then stdout:setvbuf('no') end
+	if stderr.tty then stderr:setvbuf('no') end
+
+	return setmetatable({ stdin = stdin, stdout = stdout, stderr = stderr }, mt)
+end
+
+local function writeStyled(tty, stream, arg)
+	if type(arg) == 'table' then
+		local token = tty:mark()
+		if arg.bg then tty:setBg(arg.bg) end
+		if arg.fg then tty:setFg(arg.fg) end
+		for i = 1, arg.n or #arg do writeStyled(tty, stream, arg[i]) end
+		stream:flush() --ensure
+		tty:reset(token)
+	else
+		stream:write(arg)
+	end
+end
+
+local function writeUnstyled(stream, arg)
+	if type(arg) == 'table' then
+		for i = 1, arg.n or #arg do
+			writeUnstyled(stream, arg[i])
+		end
+	else
+		stream:write(arg)
+	end
+end
+
+--[[write strings to stdout with optional styling.
+
+tables are assumed to be styled groups, ie sequences of strings/styled groups with optional extra properties:
+	.fg = 0xrrggbb sets foreground color for all contained text, unless overridden by a styled group inside
+	.bg = 0xrrggbb sets background color for all contained text, unless overridden by a styled group inside
+these properties are applied while rendering the styled group, then reverted to the prior values before rendering
+any following values in this or future write() calls.
+
+if stdout is not a tty, all styling is ignored.
+]]
+function mt:write(...)
+	local args = table.pack(...)
+	local caps = self.stdout.tty
+	if caps then
+		writeStyled(caps, self.stdout, args)
+	else
+		writeUnstyled(self.stdout, args)
+	end
+	return self
+end
+
+--write strings to stderr with optional styling.
+--see `mt:write` for how styling is interpreted.
+function mt:error(...)
+	--[[
+	local args = table.pack(...)
+	local caps = self.stderr.tty
+	if caps then
+		writeStyled(caps, self.stderr, args)
+	else
+		writeUnstyled(self.stderr, args)
+	end
+	return self
+	]]
+	return self:write({ fg = 0xff0000, ... })
+end
+
+--prompt the user for a line of input.
+--if stdout isn't a tty, equivalent to `io.stdin:read('l')`.
+function mt:prompt(...)
+	if self.stdin.tty and self.stdout.tty then
+		self:write(...)
+		self.stdout:flush()
+	end
+	return self.stdin:read('l')
+end
+
+return { wrap = wrap }
+
+-- vi: set ts=2:
diff --git a/src/livedisk/init.lua b/src/livedisk/init.lua
index 0ea28b1..f043a75 100644
--- a/src/livedisk/init.lua
+++ b/src/livedisk/init.lua
@@ -1,28 +1,6 @@
 --/etc/init.lua for the kitn livedisk and installer
 
---find highest-tier gpu available
-local bestGpu, bestMem
-for addr in component.list('gpu') do
-	local mem = component.invoke(addr, 'totalMemory')
-	if mem > (bestMem or 0) then
-		bestGpu, bestMem = addr, mem
-	end
-end
+--spawn a lua repl on each available screen
+return dofile('/bin/multitty.lua', '/bin/lua.lua')
 
-assert(bestGpu, 'please install a gpu or apu to continue')
-
-for screen in component.list('screen') do
-	local proc, err = kitn.createProcess('/bin/tty.lua', bestGpu, screen)
-	if not proc then error('spawn for ' .. screen:sub(1, 4) .. ' failed: ' .. err) end
-end
-
-local function tick(signal, addr, ty)
-	if signal == 'component_added' and ty == 'screen' then
-		local proc, err = kitn.createProcess('/bin/tty.lua', bestGpu, addr)
-		if not proc then error('spawn for ' .. screen:sub(1, 4) .. ' failed: ' .. err) end
-	end
-
-	return tick(computer.pullSignal())
-end
-
-return tick(computer.pullSignal())
+-- vi: set ts=2: