Scor­pio News


October–December 1987, Volume 1, Issue 4

Page 48 of 55

‘The 19M card (and 1 guess the others) bas some simple and stupid dedicated hardware features ‘The major houlie two sepur latches, ome which says “RD track/ad track” which relates philly tovthe ‘deve selected and the other which says. “HighiNocmal “deasty”” This could gre “us four permutations which should cover the three cases we want and one we don

Unfortunately, when “BO track” is selected, 1 jams the other Iateh so that it’s automatically high density 20 any drive assigned wut 80 tacks is automatically assumed to be high density Alto, the head step hardware always sends two ead-step pulses to the dive but in the. case of @ SHigh density” being selected « hardware ‘divide 2 divider is userted sm the head-step line to casure one sep per tack if an") track” drive is selected “and “Normal “densty” ss” asserted thea the dimder switched out to provide 4 tracks og the 80 ack dnve, and the data rale ‘witches to 250K ‘bits Thos formating « 360K disk. This explaine my nding of 2 normal BD track drive double stepping, desde beg an 80 track deve and running normal density

If “40 track” as selected, then operation.

‘That iso the end of the story, Ive since discovered «controller card which claims to sob the problem, although T haven’t tried it (im aot spending tore ‘money on something I’m prepared {0 Five With, libough Td ather not Lve with i that is). “The card is the “UDC card) from UPIC of Dunst

‘The story & continued by John and what follows is an edited vernon of long Heiter which T recewed i the mde of July. Il appears to get round the ‘problem wih one_particlar eoatroller (Everest) and throws some beginers light on to some ofthe otber pecliar aspects of MS-DOS.

jams the “Density” latch to low and forces normal 360K

John Parrott Continues

‘There are many IBM XTs and ATs at the company where I wed to work and the word was that 360k ‘disks wnilen on the high densty drives were aotonousy unreliable” Of ‘course that made some fense to me, Knowing that the diference in the bead areas docs cause 4 reduction ia the signal 10 foie ratio whens stp. recording 1 played ack on 4 Sip drive, because of the unr ‘areas (or even worse, unerased ‘6ipr trac) “seen” by the 48ipr heads,” But havng said that, 1 bave (0 ‘ay that wl the Gemuni one could get away with almost anything most of the time. Amway, the fomputer sernces people were therefore equipping their ATs wih 60K “48 drives so. that dike ould be shared around the company

‘The time came for me to buy an AT (wy, how and which are another story) and the ation of = ‘M0KB “deve was an cxsental sem on my, shopping 1st. Twat alo laolang frward to playing sith seca those Taphdesiy des.” shouldbe a olde io mule’ hem Sotaty format “1 tach E Sought a Japanese clone’ manufactured by Preese from ‘CAS Computers They fited the eta dive wie I waited snd then demonsaed the machine.

1 asked for some ds to be formatted and some programs run. All the programs ran and the Norio SI” gave. a sytem performance’ figure of 133. (alfeugh i ypically goes 13 ow tha my ‘putem fly configured) “The formatting and. dik coping were, Eovewers very worliable Slee when vsing the 1 option aod Gu 30K dnve war spiced, cvea tough’l bat seen removed ftom “ts” brand-new package. Before. changing the deve” we tied formating 1m the HD. dre ‘Thus was also unreliable Some ‘expects: wert called aid they said “ab bes you’re wsing Quad density dks aad they woot work al ip exlaned that thee. were fesb unformatted dks fod tat ay old fashioned CP/M. system had no problem an forming. theme any format chosen. I ted to Seplain thatthe HD dove was Sep anyay eter eter Bute 000 avail They thought was my dks I thought there was evidence of bug MSIDOS reaing 0 the HD lek and’ wasnt Sore about the Sk dee

1 finally persuaded them to uy another 360k dave and that sally gave the same resus as bets Ti fied torr te began MS-DOS gin epect f al oppy eT thes ucts, scored tha i read 4 pric ype of kcal format and. write

Of the same formal, DISKCOPY remained a SUSO alfur (ee a had been with the company XTs aad ‘ATs) but that ido matter Twat satshed that all the machine’s hardware wat working and the ‘experts were happy tha it ha all ben because of my disks Ie, clutching my ew toy

This is an OCR’d version of the scanned page and likely contains recognition errors.

Page 48 of 55