[Coco] Emulating a 1980 4K CoCo on PC

computerdoc at sc.rr.com computerdoc at sc.rr.com
Wed Dec 31 17:50:17 EST 2014


Hi Early 4K Coco 1 Enthusiasts,
I must say I am quite impressed with how many of you guys actually started their journey with the Coco with the very first Coco!  When the Coco 1 first appeared with a $500 price tag, if memory serves, it was a bit too high for me.  In the '81 to '83 time frame the Coco 1 with 64K was about $200 which was when I got in on the Coco journey myself.  Although I started with Color Basic v? in my Coco 1, I had 64K so I never experienced all the limitations a 4K Coco would pose.  I did know what it was like to use the all popular unreliable Cassette Recorder for Basic Program storage.  I spent hours at a time working hard to make sure my programs stored correctly many times by recording them more than once.  Did anyone else do that too?  
When I saw this 4K Coco 1 Color Basic Contest, I thought it would be both fun and frustrating to write a Basic program on a 4K Coco 1, so I finally got XRoar running with just 4K of ram and just Color Basic 1.2 with quite a bit of effort.  I tried over and over trying to get the xroar.conf file to recognize my 4K Coco configuration which by the way it never did, so I moved all the extbas11.rom, disk11.rom and hdbdw3bck.rom image files to a subdirectory called "hide stuff" and put the command line parameter "-ram 4" for xroar.exe into the icon properties on my Windows 7 laptop and as if by magic XRoar started up with a 4K Coco 1 running Color Basic.  Of course all the machines in XRoar are now 4K!  :)  
I have also had to restart writing my Basic program for the contest several times as it seems that XRoar exits quite abruptly if you press <CTRL>-C with no prompt for "Are you sure?"!  It is beginning to get a bit aggravating since I have Asperger's Syndrome, ADD, Bipolar Disorder and OCD!  ARGH!  There is quite a bit going on in my head!  How about yours?  Anyway, I'm thinking of using a real Coco 1 and try poking the top-of-ram location in low ram for Color Basic to $0FFF and see was happens.  I need to look at my Color Basic Unraveled pdf file to get that address though.  I wonder if poking that address, poking 113 with 0 and exec &hA027 will give me a 4K Coco 1?  Of course I will pull out the 24 pin Extended Basic eprom and pull out my cassette recorder again after decades and see what happens.  It will be anything but dull.  Now that I have proofread this email, poking the top-of-ram may not work.  If not, I may have to modify the Color Basic code to only have 4K of ram.  I'll let you guys know how this goes.
I'm on vacation right now, so I won't be able to test all this out until I get back home this Saturday.  If any of you are in the Myrtle Beach Area or close by, I'd like to meet you.  Take care my friends.

Kip Koon
computerdoc at sc.rr.com
http://www.cocopedia.com/wiki/index.php/Kip_Koon




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