CoCo 2 - query on ID error with Coco SDC

[1980s_john]

Hi,
I have just bought a Coco SDC for my Radio Shack TRS-80 Colour Computer 2 (yes its a UK version with correct spelling!) . Machine is part number 26-3136A, currently has 16K RAM (64K chips on order). I copied the contents on the Coco SDC zip : https://colorcomputerarchive.com/repo/Disks/Coco SDC/Image/ to a freshly formatted SD card, first up on booting it gave an OM error (out of memory), rather than loading the SDC front end. From the OK prompt I can browse and mount disks fine, I am trying to run Tetris but get an error as follows.

DRIVE
shows current SDC drives OK. I then set drive 0 to be the Tetris disk:

DRIVE 0, "GAMES/T/TETRIS
DIR

shows the Tetris binary file, but when I run:

LOADM "TETRIS
the Coco gives:

?ID ERROR

What does this mean please? What small Basic games should I try and load first in 16K?

I'm not sure if Tetris may need a machine with a later Basic, mine is version 1.0.
Any help appreciated, I'm a Coco newbie but the SDC is brilliant add-on.

Regards,
John

 

[1980s_john]

Hi,
I've checked Color Computer 2 Quick Reference card, says ID means Illegal Direct. So what does that mean please?

Regards,
John

 

[Bruce Tomlin]

?ID error is "Illegal Direct", which is what happens when you do a command that isn't supposed to be used at the command line. Checking a disassembly of BASIC, it looks like that is only generated by INPUT, LINE INPUT, and DEF FN. So something screwy is going on. It's possible that the file you are loading is simply scribbling over memory that's being used. You could maybe try PCLEAR 0 first, I dunno.

LOADM loads a binary, so it's hard to tell without looking at what addresses the file wants to be loaded at.

 

[1980s_john]

Thanks, the problem seemed to be down to insufficient RAM. With the SDC plugged in (and booting to Disk Basic)

PRINT MEM
gave 6317.

I tried PCLEAR 0 but this gave ?FC ERROR

Anyway, my 64K RAM arrived today (bargain at £3.88 delivered), plugged the two D41464C-10 chips in and soldered a short jumper wire in. Now PRINT MEM gives 22823 with the SDC plugged in, and when rebooted the machine goes straight into the SDC file browser which is really simple to use (thanks to the developers on this).

I loaded TETRIS and it now runs fine, apart from no colour - my machine is PAL (has the standard UHF TV modulator output only, no RGB goodness) and I think most games were NTSC. There are hundeds of programs in the SDC zip to play with, so I guess I am sorted

Regards,
John
PS Next up - Dragon 32!

 

[Satyr Icon]

PCLEAR 0 is not a literal thing. Everybody using a stock BASIC will get that error if they try it. The phrase "PCLEAR 0" refers to an assembly language trick to recover memory from the graphics system for other purposes.

PCLEAR 0 to get more CoCo BASIC memory

Updates: 2021-12-15: Added screen shot of BASIC ROM assembly. On the Radio Shack Color Computer, Extended Color BASIC added new commands to access high resolution graphics modes. The following mode…

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