Scor­pio News

  

October–December 1987 – Volume 1. Issue 4.

Page 14 of 55

memory. As for software support this is then care of by the CP/M BIOS – I don’t have to do anything extra to user drive P:.

The only problem with RAM instead of disk is that it is volatile. You must obviously remember to re-save to disk of interest before switching off or suffering a power cut !!!

DH. may hardly ever use his virtual disk, but for me it makes life bearable.

Michael Newson, Banbury, Oxon.

BDOSZ Fixes

Dear Sir,

Many tjanks for publishing my last letter in which I offered free upgrades for BDOSZ. The response to the letter was absolutely overwhelming and all four people should have their updated copy by now. Since the last letter, BDOSZ has now had a couple of minor alterations and one small bug fix, and the version now stands at 1.02.

The bug caused data written to a previously allocated sector to be forgotten when the file was closed. A typical example was under ZAP or SPZ where the first record of a file was patched and ZAP exited. Some users found that the changes hadn’t been written to disk. The problem was that although the data was sent to the BIOS, it remained in blocking/​deblocking buffer. The BDOS wasn’t causing the buffer to be flushed when the file was closed, and the buffer was discarded on warm boot.

The bug fix is published below and is valid, certainly for all versions from, 1.6 onwards The unmodified code is shown in full. The change involves deleting those lines indicated ‘ <--- ’. My thanks to Philip Sherlock of Kenilworth Computers for bringing this bug to my attention.

For those who obtained an upgrade to version 1.8 ( the last version issued to Henry’s Radio for distribution) and who are wondering whether they have missed out, versions 1.9 and 1.91 only added options to revere the effect of the Backspace and Delete keys or to make them both Backspaces. They also offered improved Control-S handling so that the Control-S is no longer ignored if there is already a character waiting in the BDOS character store (try pausing M80 if you have it sending the listing file to the screen if you have already typed another character). The penalty for this second improvement is that the BDOS will now steal type-ahead characters – this why the feature is optional.

My offer is still open for those who have yet to upgrade their versions of BDOSZ. Please send your BDOSZ distribution disk to the address below, enclosing your name and address together with U.K. postage stamps to cover the cost of returning it to you. Overseas readers may send a cheque payable to M.W.T. Waters.

Yours sincerely, M.W.T. Waters, _ _________ _____, Stanmore, Middx. ___ ___.


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