8-Bit Software Online Conversion

D6G Sprow 999 SUBJECT - ANSWERS TO QUESTIONS Printer Dump inverter ===================== A couple of issues back Syd Hetherington was having problems printing out screen dumps that he had scanned/digitised. I can't remember whether I sent my response - so here it is anyway. Use VDU18,3,129,16 This will make the OS EOR all the screen memory bytes with 255, resulting in the whole screen being swapped black for white. This should result in your screen dumper printing out properly. An example use might be: 10MODE0 20*LOAD filename 3000 30VDU18,3,129,16 40*DUMPSCREEN (or whatever) Hope this is of help in saving you ink! Osword &7F ========== Even further back in the myths of time a puzzled member was in search of a 1770 equivalent to the "Advanced Disk User Guide". Well,I don't have one either,but I do have a chart of how the new 1770 commands map onto the old.In general Location Contents --------------------------------------- BLOCK+0 DRIVE# (0-3 OR FF FOR SAME) BLOCK+1 DATA ADDRESS LOW BLOCK+2 DATA ADDRESS HIGH BLOCK+3 HIGH ORDER (FF OR 00 IF I/O ONLY) BLOCK+4 AS PER BLOCK+3 BLOCK+5 NUMBER OF DETAILS (0-3) BLOCK+6 COMMAND CODE (SEE BELOW) BLOCK+7 1ST DETAIL (USUALLY TRACK#) BLOCK+8 2ND DETAIL (USUALLY SECTOR#) BLOCK+9 3RD DETAIL (USUALLY SECTOR SIZE + NUMBER OF SECTORS INVOLVED) BLOCK+10 RESULT RETURNED HERE The result code will appear earlier if less details are supplied,ie.at block+8 if only 1 detail is reqd. Command Code Details --------------------------------------- Seek &69 Track# Read status &6C None Write spec reg &5A Reg#,data Read spec reg &5D Reg# Read sectors &53 Track,sector,# of sectors to be read Read deleted &5B Track,sector,# of sectors to be read Read ID &5B # of IDs Verify sectors &5F Track,sector,# of sectors to verify Write sectors &4B Track,sector,# of sectors to write Format &4B Track,Gap3-6,size/ # of sector,Gap5-6 Gap1-6. The seek command moves to head to the specified place. The status byte returned for read status is returned in one byte,with bits 0 and 7 set to zero. D6 D5 D4 D3 D2 D1 RDY1 WRTFAULT INDEX WRTPROT RDY0 TRACK0 Anyone who buys the £30 1770 machine off me can have the entire of this manual - it's too much to type in! FX3 - the full story ==================== I made a typo in the QUIDFIX program, and last month suggested you try FX3,10 instead. Someone wrote to me asking what this meant in terms of bit patterns,well, I'll send you the Acorn application note on the subject if you want. It can be emailed to you,or posted.See the *CUSTOM section of my forsale list for details about app notes. Disk speeds =========== John Robson (D8J) was experiencing drive problems with a Master.Assuming they were the same make of drive,with the same option link settings inside one can assume that it is the computer at fault. Using two different Masters to test this on would lead me to think that they had different drive controllers in - early Masters had 1770's in, the later issues (mine has) a 1772 in. These interpret the FDRIVE configurations slightly differently, so even if both machines had the save software setting the hardware may be thinking otherwise. They are: Value Step time Precomp? WD1770 WD1772 0 or 4 6ms 6ms yes 1 or 5 6ms 6ms no 2 or 6 30ms 3ms yes 3 or 7 30ms 3ms no Most drives require 6ms step time. Older drives may need the 30ms step time; modern drives may be able to operate at 3ms - consult your disc drive documentation. Factory default : 0 "Precomp?" indicates whether, when using ADFS, precompensation will be used. The rest of this configuration application note is available - see *CUSTOM section for more details. You also said they were cutting out, this I attribute to a dry joint or similar poor mechanical problem,such as overheating or cracked track. The relay that clicked randomnly for you may well be a serial ULA problem as this is what used to control it on the BBC B. If you're still having problems, contact me and I can of course have a look at it for you (see the regular contacts section under Sprow Cubed) Magazines ========= I myself don't know what happened to The Micro User and Acorn Computing but I've a feeling someone told me and it went something like this: BBC Micro user changed name to The Micro user after the BBC moaned about copyright. In parallel with this Acorn Computing mopped up any Archimedes stuff.When interest in the BBC fell,the two merged to form Acorn Computer User which as a remarketing ploy (cf. Snickers and Marathon) renamed themselves as Acorn User.That brings us right up to 1996. Please do correct me if I've missed anything out in this history. Keep BBCing! Robert Sprowson.