Howard Herman wrote:
> Subsequently, when Basic 8 programs began to appear both the flat C128
> and C128D had display problems, and I upgraded both computer VDC chips.
> As I recall these were relatively expensive, something like $30(US) each
> at the time. But the new VDC's let me successfully run all the new
> Basic8 programming.
Do you have version information of the VDC chips you removed and the
ones you got as a replacement? I know that there are some issues when
programming bitmap graphics with the very early 8563 VDC, but it can be
fixed in software. Since the 128DCR was never shipped with a 8563 at all
but with a 8568 I'm very curious why you had to upgrade that chip.
The VDC has a software version register, and you can use it to determine
your VDC version from software:
Chip version
8563R7 and lower 0 (this needs special treatment for
bitmap)
8563R8 and higher 1
8568 2
You get the version by reading the lower 3 bits of the VDC status
register at $D600. PRINT (PEEK(DEC("D600")) AND 7) should do this.
Nicolas
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