APPENDIX EIGHTEEN

Changing The 400/800 OS On The XL/XE Computers

When you boot the Translator disk, use one of the commercial "fix" disks (such as FIXXL), or run Matt Ratcliff's "ROM OS to RAM OS" pro- gram (Appendix 19), you turn your OS from ROM based to RAM based. This allows you to change it by POKEing directly into mem- ory. When you use the Translator or the Allen MacroWare XL BOSS chip, you have the 400/800 operating system in memory instead of the XL/XE OS. This section describes many changes which can be made to the 400/800 OS when in the XL/XE RAM. In all cases, Revision B OS is de- scribed since the Translator and Allen MacroWare don't use the Re- vision A OS. These changes can be POKEd into memory if you have the Translator booted or the XL BOSS installed. For 400/800 owners, if you have the hardware for making your own PROMs or EPROMs, you can make these changes into the PROMs and replace them in your OS board. The same applies for the Newell Industries RamRod board. I have tested and used both the Newell RamRod and the Allen MacroWare XL BOSS and consider them both excellent products and highly recommend them. Much of the following material was de- rived from their manuals.

57344 E000 CHARSET1

You can change the character set directly by POKEing here rather than reserving space in memory for an altered set. See the section on character sets in the main memory map and 54017 ($D301). (XL/XE users can change this and the inter- national set also.)

59497 E869 ....

The interval for the keyboard repeat. The original value is 6; POKE with 3 to move the cursor twice as fast for repeating characters (XL/XE also).

60294 EB86 ....

To increase the cassette baud rate by almost one-third and re- duce the time of the leader from 20 to 10 seconds, POKE the following: POKE Address Value Hex 60294 00 $EB84, $00 low byte, write baud 60299 04 $EB8B, $04 high byte 61250 00 $EF42, $00 low byte, baud rate init routine 61255 04 $EF47, $04 high byte 61346 00 $EFA2, $00 baud rate open routine 61351 04 $EFA7, $04 high byte 61371 02 $EFBB, $02 leader time

61683-61707 F0F3-F10B ....

Memo pad mode startup message; "ATARI COMPUTER - MEMO PAD (CR)."

61709-61718 F10D-F116 ....

BOOT ERROR message. This is at 50237 ($C43D) in the XL/XE.

61812 F174 ....

Left margin default; initially 2.

61816 F178 ....

Right margin default; initially at the maximum 39 ($27).

63227-63229 F6FB-F6FD ....

Key click sound, change these three bytes to 234 ($EA) to dis- able the key click sound completely.

64728 FCD8 CLICK

You can also remove the click sound by changing the first byte of the routine here to 96 ($60; RTS).

64729 FCD9 ....

The buzzer/bell time for warning sound prompts. Initially 127 ($7F), you can reduce it to any time; 63($3F) is half the time. This location also affects the key click sound time.

65217-65221 FEC1-FEC5 ....

Default (startup) color value tables. These values are moved to the shadow registers 708-712 ($2C5-$2C8) on power-up or RE- SET. The screen startup is blue; to change it to black, POKE 65219 ($FEC3), 0.

65278 FEFE ....

The keyboard table; you can redefine the entire keyboard by POKEing here (see the XL/XE map section). One trick is to change the keyboard so that the cursor (arrow) keys work on pressing, and you have to press SHIFT and arrow to get -, =, +, and *, and CONTROL and arrow to get , , , and . Do this by: POKE Address Value Hex 65284 30 $FF04, $1E 65285 31 $FF05, $1F 65292 28 $FF0C, $1C 65293 29 $FF0D, $1D 65348 43 $FF44, $2B 65349 42 $FF45, $2A 65356 45 $FF4C, $2D 65357 61 $FF4D, $3D 65412 92 $FF84, $5C 65413 94 $FF85, $5E 65420 95 $FF8C, $5F 65421 124 $FF8D, $7C (XL/XE owners: Your keyboard definition table begins at 64337, so to use this modification, subtract 941 from the addresses given above.)

65281 FF01 ....

1200XL owners: You can use your function keys as cursor keys by POKE 65281, 30 ($FF01,$1E), POKE 65282, 31 ($FF02,$1F), POKE 65297, 28 ($FF11, $1C) and POKE 65298, 11 ($FF12,$1D).

65487 FFCF ....

XL/XE only: To make the HELP key a start/stop key equivalent to CONTROL-1, POKE here with 17 ($11). The HELP key returns a keycode value at 732 ($2DC) of 17 ($11) for normal use, 81 ($51) for SHIFT+HELP, and 145 ($91) for CONTROL+HELP.

65507 FFE3 ....

The time delay for the repeat feature; initially 3; POKE with 1. See also 65516 (FFEC) below.

65516 FFEC ....

Key repeat delay. Initially 48 ($30); change to 15 ($0F). Do this in conjunction with the change at 65507 ($FFE3).

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