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Tandy 1000 RLX and RSX BIOS Modifications

Cloudschatze

Cloudschatze

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Here are a couple of modifications that I've made to the Tandy 1000 RLX and RSX BIOS ROMs. The primary focus was to update the VGA BIOS, and thereby gain access to additional video modes and compatibility/functionality enhancements that had required the use of a software-loadable video BIOS otherwise.

For the RLX-A and RLX-B, the additional video modes are as follows:

Mode 54, 132x43, 16-color (text)​
Mode 55, 132x25, 16-color (text)​
Mode 56, 132x43, Monochrome (text)​
Mode 57, 132x25, Monochrome (text)​
Mode 58, 800x600, 16-color (graphics)​
Mode 59, 800x600, Monochrome (graphics)​

Of note, the 800x600, 16-color mode is compatible with both Windows 3.1's Super VGA driver and the comparable "VESA" selection in GeoWorks and NewDeal Office.

An additional set of images provided for the RLX-B includes a ROM-drive-disabling workaround for use with the XTIDE Universal BIOS, in conjunction with an applicable adapter card, and in lieu of needing an XTA drive installed in parallel. This workaround is not necessary for the RLX-A.

The modified RSX BIOS image includes Cirrus Logic VGA BIOS version 1.20, which permits the use of the 800x600, 256-color mode in Windows 95, using the native, "Cirrus Logic" driver selection.

Tandy 1000 RLX-A
27C400 EPROM or compatible, 150ns or better

Tandy 1000 RLX-B
27C400 EPROM or compatible, 150ns or better

Tandy 1000 RSX
27C1024 EPROM or compatible, 150ns or better
 
Does it change the 1000RLX's text mode font into something less blocky and ugly? Even the standard IBM VGA font would be an improvement.
 
vwestlife said:
Does it change the 1000RLX's text mode font into something less blocky and ugly?
Click to expand...
I'm admittedly indifferent/oblivious to some of the nuances, but the updated font does seem fairly similar to that of the IBM VGA font.

Not-great photo of the RLX-A text output with the updated BIOS:

rlx_vga_font_s.png


I would be happy to program and send an RLX-A EPROM your way, if that's anything you'd be interested in.
 
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I showed a close-up of the RLX-A's text mode font and how it affects readability on the notoriously grainy Tandy VGM-220/225 monitor at 7:27 in this video:

 
vwestlife said:
I showed a close-up of the RLX-A's text mode font and how it affects readability on the notoriously grainy Tandy VGM-220/225 monitor at 7:27 in this video:
Click to expand...
Ah, gotcha. I can see that there are definite differences between the original and updated fonts, especially concerning some of the character serifs.
 
Here are two alternate BIOS modifications for the RLX-B. These leverage a slightly-different video BIOS version that runs the 800x600, 16-color mode at a "standard" 56/57Hz vertical refresh rate, rather than the ~59Hz rate of the earlier-posted release.

I only discovered that this was even necessary when attempting to use a different (older) LCD monitor today, and finding that it couldn't properly size/scale the 800x600 output from the system, resulting in a vertically stretched image with no monitor-provided means or mechanism for adjustment - auto, manual, or otherwise.

Tandy 1000 RLX-B
27C400 EPROM or compatible, 200ns or better
 
I would be interested on 27C400 EPROM for my RLX-B with the VGA BIOS update + XUB workaround: 8079074_XUB_VGA-BIOS-VER-B-1.00-07.BIN
I just purchased a PicoMem nor realizing the HDD issue on this model. FreddyVRetro pointed me to this thread to see if this would solve the issue I have.
 
rbarquer said:
I would be interested on 27C400 EPROM for my RLX-B with the VGA BIOS update + XUB workaround: 8079074_XUB_VGA-BIOS-VER-B-1.00-07.BIN
I just purchased a PicoMem nor realizing the HDD issue on this model. FreddyVRetro pointed me to this thread to see if this would solve the issue I have.
Click to expand...
It worked great for me and my RLX-B. Was a bit of work though. I had to get an adapter for my EPROM programmer and then order the 27C400 before I could program it. But once programmed, I swapped the EPROM with the original BIOS chip and the PicoMEM worked.
 
I would be interested too! I just did the same, went from Lo Tech XT-CF lite rev 2, to Lo Tech IDE SD wondering if it would work, back to the XT-CF which is working on D800/300 and booting to CF by setting the boot device to 82h. But it would be nice to disconnect the Seagate!

rbarquer said:
I would be interested on 27C400 EPROM for my RLX-B with the VGA BIOS update + XUB workaround: 8079074_XUB_VGA-BIOS-VER-B-1.00-07.BIN
I just purchased a PicoMem nor realizing the HDD issue on this model. FreddyVRetro pointed me to this thread to see if this would solve the issue I have.
Click to expand...
 
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