Archive for October, 2013

Orwell load and save working (mostly)!

October 31st, 2013

Today I managed to get my LOAD and SAVE routines working. Took me bloody ages and the issue was one that I’ve been bitten by before (and haven’t learned from obviously). Save turns out to be trivial due to the way my computer works. I didn’t need to do anything. The way I am implementing […]

Review – Usborne Guide to Computers.

October 28th, 2013

As this is my first review I better explain how this works. I grew up in the era of the microcomputer and the home computer in the early 80s. Before this computers were either mainframes or minicomputers. The sort of large, expensive computers only seen in universities, large corporations or the lairs of Bond villians. […]

Orwell REALLY running Basic.

October 28th, 2013

Finally, after weeks of painful debugging, I worked out why Basic wasn’t running. It seems in the OSI code there is a bug in the control-c handler. If you look in the original code for MS Basic you’ll see it in the osi_iscntc.s file you see: .segment “CODE” ISCNTC: jmp MONISCNTC nop nop nop […]

Orwell running BASIC. Well, mostly…

October 5th, 2013

After much fiddling about I finally got MS Basic running on Orwell. Well, mostly. Firstly I fixed some bugs, one a hardware error. The reason my IO port was showing LEDs lit when nothing was writing to it was because the way the address logic was working it mean the output latch was inadvertently being […]

Orwell keyboard input and Microsoft Basic.

October 2nd, 2013

Well, things are progressing. After a bit of fiddling I got the keyboard to work. A few wiring issues (bloody breadboards) then a false start on the key debounce code and then I got it right. Basically one port of the VIA is used to drive the 4051 analogue multiplexer which is used to pull […]