8bit Projects For Everyone


Find   for  

8251 interface

NETMX upgrade

Have you seen network interface inside Timex Computer 2048?

Some Timex Computer 2048 have mounted extra board with 8251 serial transmitter/receiver. The USART is seen in ports #FDFD and #7FFD. (#FDFD is incremented to #FDFE to read <A> key.)

Clock signal for 8251 is taken from colour crystal 4.433619MHz and after division by 2 provided to CLK of 8251 (2.2168095MHz). After division by 16 provided as /TxC and /RxC (277101Hz). 8251 is programmed to use 1/16 of this cycle: 17319bps (8 bits, 2 stop bits).

On the EPROM was written "SLD100RPCR" code - in #04B0..#04C1 addresses are the following bytes: "sld100rpcr". This is part of first difference to Timex Computer 2048 ROM (addresses #04AB..#04C4). The writing to starts at #04C2 - here is CALL #38E0.

BASIC syntax is extended to support the 8251. Extra commands are: LINE IN, LINE OUT, LINE DATA, LINE STOP.

CommandDescription
LINE DATAEnables extended syntax. Keywords followed by asterisk (*) are allowed with any syntax behind. While execution the whole command till end of line is send to network.
LINE STOPDisables extended syntax. Keywords followed by asterisk (*) cause usual error.
LINE INCan be interrupted with <A> key.

Junet and Elwro 800 Junior

8251 is build-in in Elwro 800 Junior, where works as network interface. The network is used for disk access and forcing action (can generate NMI).


Tell other people:

Files for download

netmx1-1.zip 71.1kB (2006-04-15 15:05)
NETMX v1-1 board documentation. Eagle data files.
TC8251.GEN 10.4kB (2006-04-08 15:10)
Unfinished source code of ROM changes.
tc8251.zip 12.9kB (2006-04-04 14:51)
EPROM contents read from upgraded Timex Computer 2048.
kif_3483.jpg 118.7kB (2006-03-31 01:05)
Second one (V 1-1). Open case view.
kif_3482.jpg 102.7kB (2006-03-31 01:03)
Second one (V 1-1). Open case view.
z1.jpg 45.1kB (2004-01-27 22:29)
Serial interface board mounted in Timex Computer 2048.

Links to other pages



See also

Elwro 800 Junior
Elwro 800 Junior - ZX Spectrum clone produced in Poland. Also works under CP/M 2.2 (CP/J) with access to disk drive via a network.

E-mail:

Password:



Forgot password?

Register?
CPC
4MB RAM
Flash ROM
To 128
Sam Coupé
SAM512
Portfix
YABUS.Z80RTC
Z80JOY
MSX
Mapper 4MB
MSX-2 SVI738
Spectrum
FlashD0
8251
AY
Eniac'owe
Dock
Gama 192
Keyboard
ROM replacer
SamRam
TC2144
To 128K
To +3
Wonder RAM
Z80JOY
ZX 4MB
ZXMUX
Timex
Memory
Timex FDD
YABUS.TF
YABUS.TF3
TI-of-TTL
ZX81
Memory

If you see error on this page, describe here:

© 2009-12-28 21:50 Jarek Adamski, http://8bit.yarek.pl