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Tandy 1000 SL (and others) replacement ROM chips?

C

CarlosTex

Experienced Member
Joined
Mar 26, 2013
Messages
272
Hi everyone,

my Tandy 1000 SL comes with a couple of HN62312APC55 ROM chips made by Hitachi, and my BIOS version is Tandy 1.04.00. Since these parts are impossible to source i would like to find a pin compatible part, that will work on the Tandy 1000 SL sockets. This way not only i could upgrade my SL with ROM version 2.00.01 but also have the peace of mind of guaranteeing the machine operation in case of ROM failure. If you think that never happens consider this: My IBM 5160 suffered from a dead U19 ROM, took me hours and some pulled hair until i understood what was going on. So if you think mask ROMs can't die....well go figure.

The Hitachi part seems to have been made exclusively for Tandy needs, there's no information online about it, no datasheet whatsoever, only a small reference on o2xygen electronics old stock sellers.

It's a bit worrysome that if one of these ROMs die the whole machine is bricked. There's got to be a solution.

I was also wondering if in case of finding suitable replacements, the DOS ROM could be eliminated thus freeing the E000h segment for another 64kb of UMB.
 
wesleyfurr said:
I wasn't aware that there were two different BIOS versions for the SL...what's the difference between them?

Wesley
Click to expand...

Here's my SLE/s dump.... :)View attachment tandy_1000_SLE_Bios_Files.zip

Both >E000 and >F000 (128K total)

Also, the tech manual for the SL might have the pinouts of the sockets, so just finding a pin compatible EPROM would work. My WS-1000 actually has an odd and even EPROM in it (16K x 2) with just the BIOS. No DOS in ROM, etc. The archive does have the ROMs that were on the add in ISA card (including a boot rom with the Tandy terminal emulator!)

View attachment 1000ws-roms.zip
 
Thank you so much for this! Now i just need to figure out the pinouts and get some compatible EEPROMS.
 
wesleyfurr said:
Yeah, I'm still jealous of that one... :) Did you ever determine what (if anything) is different between the SL and SL/E?

Wesley
Click to expand...

So far, the only differences is that it’s more of a SL/2 than a SL. The embedded Deskmate for a SL throws a slight error on startup with the SL/E, and I’m still trying to get my hands on the SL/2 Deskmate variant to see if it works properly. It works once you get past the error, it has something to do with loading a config file at startup. The setup SL program seems to work.

I’d really like to get a complete set of disks for a SL/2 to see if they fix these issues.
 
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