Thread: Zx81
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Old 28th Mar 2020, 7:40 pm   #212
duncanlowe
Octode
 
Join Date: Jan 2016
Location: Stafford, Staffs. UK.
Posts: 1,808
Default Re: Zx81

The POKE command reminds me of my schooldays. The school bought a TRS80. Very few were allowed near it, but of the pupils only two of us were. We were trying to develop a game. To put something on screen we would POKE a value to the graphics RAM. So during our experiments to do this, we would POKE a character to the first location, then POKE a blank, then add one and POKE a character again. A loop would then get the character to move to each location on screen. Problem is we miscalculated the number of character positions, and we think we ran over the end of the video RAM and into ROM. Whatever the actual explanation, it broke the computer. I'm quite happy for someone to prove me wrong and tell me that ROM wasn't immediately after video RAM on a TRS80 or any other explanation, but I'm still fairly convinced it was a design flaw. So POKE with care.
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