Saturday, 28 March 2020

RetroChallenge April 2020: The Devil's Whist

Bit of an early start to the the RetroChallenge Retry proposed by Mr. Sherman, but I have added to my JGGAME14.DSK in my Coco distro the program "Devil's Whist" from the Australian Coco magazine December 1986. It is a two player variation of the game Whist, which is itself a simplification of contract Bridge. One of the players is the computer. Bob Delbourgo has created what seems to be a pretty adept AI to play against.

Since the MC-10 and Coco video MC6847 video chip lacks any native characters for the card suits the author uses colours to represent the four suits instead. However, one of these colours is green, which creates problems in terms of contrast with the regular green screen background.  I think in the original program, the author switches the screen to the alternate orange color set in order to provide this contrast.  However, since the MC-10 can't display this alternate color when any sounds are played, I modified the program to use a black screen for the areas where the card hands are displayed.  However, in the main info display there was still a need to contrast the green suit, so I switch that suit to being not just the colour green but the diamond/asterix character.  So at least there is one of the more traditional card suits being used.

There are lots of nice sounds used in the program. Since they used the PLAY command, I translated them to use my special subroutine to play lists of notes from such commands, but using the regular SOUND command of standard Micro Color Basic. So not only will this program now run on an MC-10, it can also be used by 16K Color computers with only Color Basic. I have also created a version for the Dragon and added it to my Dragon Distro:

I also use a slightly modified version of my standard reverse video routine. This one uses AND 64 to select the correct character for polking to get proper reverse characters. Don't know if it is any faster, although the routine is one character shorter in length, but I think it might be. I should run some benchmarks to find out.

The program also replaces the instances where changes are made to character strings using the MID$ function. The MC-10 does not support the ability to use MID$ to "splice in" new character sequences into existing strings. So although Micor Color Basic can support using MID$ to "cut" a selected part out of a string like this:

10 S$=MID$("***JIM***",4,3)

which will result in S$ containing "JIM," the following cannot be done:

10 A$="***   ***"
20 MID$(A$,4,3)="JIM"

which will result in the output "***JIM***." Instead, I had to using a special subroutine that allows strings to be poked into existing strings, which recreates this functionality built into Extended Color Basic. This  subroutine uses the VARPTR function to determine where a string is stored in memory in order to poke the new characters into that string. It probably slows things up a little, but I have used all my techniques for increasing execution speed, which hopefully means the program does not run much slower than the original. Still there is a little delay while cards are shuffled (about 10 seconds) and sorted. That's just part of the charm of such old 8-bit Basic programs that we were willing to live with. Back in the early 80s we were just impressed that the computer could be turned into any kind of "artificially intelligent" opponent for games. They were pretty heady days. We were even willing to manually type-in programs to see such capabilities demonstrated, which I had to do today as well, since the scan was not clear enough to even bother trying to use OCR.

So my thanks go out to Bob and his nifty little computer AI driven game.

P.S. There were some corrections and improvements presented by the author in a followup edition of the Australian Coco magazine (Feb 1987), page. 41. I integrated them into the program. Now the program makes sure you follow suit if possible (i.e. now you can't cheat). Again, I had to use a special subroutine (lines 8 and 9) to recreate the INSTR function used in the update because that function is not available in Micro Color Basic for TRS-80 MC-10.

Saturday, 21 March 2020

Some New Text Adventure Ports for Coco and Dragon

Inspired by the spirit of the CocoChallenge suggested by John Linville for this year's now cancelled CocoFest I have created Coco and Dragon versions of the following text adventures: Dogstar, The Time Machine (translated from Dutch), Night of the Vampire Bunnies (by Jason Dyer), and The Mystery of Flagstone Manor (one of the First Australian text adventures). Also included on the JGGAME14.DSK in my Coco distro is a bonus program "Mindbusters" from Compute! Magazine April 85.

Time Machine
The Dogstar Mission - Lance Micklus
Flagstone Manor
Night of the Vampire Bunnies

The Compute! program is an interesting puzzle game.  The program is very simple, but elegant.  I have seen images for it for many years on the Net as I have scoured for Basic code. Finally, I decided to make a version for the MC-10, Coco and Dragon. The graphic characters are a little different, but I hope the game play is much like the original.

Translating the BASICODE program "De Tijdmachine" to English English was not as hard as other efforts I have made at translating text adventures from other languages, such as the Hungarian A Hös Lovag. Dutch translates in a pretty straightforwardl way into English. Still, there were, as always, a few idiomatic phrases that Google couldn't translate that I had to figure out.

It was interesting finding out about the BASICODE standard, which was used to create programs and then to broadcast them using radio signals for distribution. Gareth Pitchford sent me a link to a neat page with a UK perspective on BASICODE: And another one with the Dutch perspective on this interesting early attempt at a universal inter-computer information exchange format:  Unfortunately, I had to strip out all the extra (unused) subroutines at the beginning of the program that were part of this standard. I also had to renumber the lines to save space, which also disrupted the standard, since it had specially assigned ranges of line number for putting its subroutines, and other standard parts of  programs.

I have played the games through using walkthroughs, so they should be bug free. That being said, Miyagami Noriko from the Coco Facebook group played through Dogstar and discovered that the misspelled word "HEROS" appeared in the win message, which I have now corrected. She pointed out that this misspelling was in the original Softside magazine source and that I had corrected the "Hamberger" spelling mistake that could also be found in that source. She also pointed out a missing message about the Graffiti in the Bathroom. So thanks to Miyagami for her feedback.

Hope everyone is doing well in the face of Covid-19. Perhaps these programs will help folks while away some of the hours as we all try to do our part.

The program can be found here:

On JGGAMES14.DSK of my Coco compilation: ... TN0a2Q1bGc

TIMEMACH.CAS, DOGSTAR.CAS, BUNNY.CAS, and FLAGSTON.CAS are on my Dragon Compilation: ... klURW9DNTQ

Sunday, 15 March 2020

Type-in Mania 2020 Awards

The contest rules are as follows:

The player who can achieve and post (screenshot or video) evidence of the highest score in a public forum by April 19th  Saturday April 25th 2020 earned playing my Basic game MINER will win a "Type-in Mania 2020" trophy that I will send to them.

Manic Miner

A second trophy will be awarded to the first person to complete my Basic game ADVENTR by retrieving the chalice and taking it to the Yellow Castle with the highest level (1-3), and also having retrieved the micro dot and used it (dropped it) in the correct location to reveal the secret entrance to a secret room. They must record evidence of the message that can be found in the secret room and their winning screen (screenshots or video) posted on a public forum (Coco Facebook, MC-10 Facebook, Youtube, etc.) before the end of April 19th 2020 Saturday April 25th 2020.

Atari Adventure in Basic
Last year the award went to George Phillips for achieving high score on my game Dam Busters.  His  score earned him a Distinguished Flying Cross and a Victoria Cross!

George's Win

Victoria Cross

If people have suggestions for alternative original games of mine they would prefer to play for high score for this year's Type-in Mania awards, let me know. I will consider  possibly adding a 3rd trophy. Or perhaps I will simply get some specialty mugs made. Feel free to arrange online game playing sessions in any forum that might get arranged for a "virtual CocoFest" or sessions at any time between now and the deadline. You can contact me at to let me know.

My games can be played using Mike Tinnes' online Javascript MC-10 Emulator or Tamer's VMC10 emulator by download. To play the game online click the following"Play" button and then select the "Play Our Original Micro Color Basic Games" link and select the filename (MINER or ADVENTR) from the Cassette menu. Then type RUN and hit Enter. You don't need to type CLOAD. Or choose the "Download" link to download a zip with the VMC10 Emulator. The two .C10 tape files can be found in the JimG directory of the Cassette directory.  In VMC10 you will need to type CLOAD to load these .C10 files.

The games can also be played using Coco by downloading the following compilation of my virtual coco disks. The latest versions of MINER and ADVENTR (with some updates from last year) can be found on the JGGAMES12.DSK:

They are also available for Dragon 32 as .CAS files:

These can be played online using XROAR here:

P.S. And the Winner was:
Darren Ottery with 10500

A strong second place was achieved by Jerry Young aka Pitfall Jerry with 7900:

A winner's mug/cup will be sent to Darren.  Thanks to everyone who tried my game!
On the other side of the mug it says:

Type-in Mania Winner
On the TRS-80 MC-10