20-04-2022, 04:34 PM
(20-04-2022, 03:56 PM)Snuffytime Wrote: I was fortunate enough to recently obtain one of my "Holy Grail" machines - a Premium Series PC85 colour 'Bee which I want to upgrade to add mass storage. But there are some other possible options such as expanding the attribute/PCG RAM to 32k, adding the SN76489AN and amplifier, and adding the RTC. Which of these are worthwhile? That is, is there much existing software which takes advantage of any of these upgrades?
Hi Snuffytime.
>Attribute ram / 32k PCG
While it is possible to upgrade the video memory the only software I know of that uses the expanded ram is user created.
By that I mean, I've not seen any commercial software take advantage of expanded video memory.
Here's why :
* expanding the Screen / Colour / Attribute ram from 2K to 8K static rams theoretically gives you video 'Pages', however,
in practice there were some unwanted side effects making the machine unusable.
* 32K of PCG was a good option, but a very low percentage (next to none) came out of the factory that way so there was
little incentive to write software to make use of it (very limited market)
* 64 x 16 screen mode was fully catered for with 8 banks of PCG which was the most common video mode software was
written for. 80 x 24 screen mode would need the extra banks if a full bit mapped display was to be utilized, but word processors
(Simply Write) and comms packages (Telcom) were the most common 80 x 24 / 80 x 25 screen mode programs and didn't
need the additional graphics ram.
The Premium Plus upgrade (which might be a good way to add mass storage to your Premium -
http://www.microbeetechnology.com.au/sto...grade.html ) does upgrade the PCG Ram
to 32k and eventually I would like to provide another graphics mode for basic (HIRES / HIRES2 / <HIRES3>) which would give
640 x 256 fully dot addressable graphics. The scheme uses 10 PCG banks and it is something that will be implemented for the
up-coming Classic-Plus kit.
>RTC / SN76489
The system software does support the real time clock if it is fitted, but will need an update for 2000 Century to be usable.
There is no [commercial] software support for the SN76489 in the bee, so it would only be of interest if you wanted to write
your own routines to use it.