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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.
 
Last edited:
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.
 
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