The Sinclair QL Forum

Hi Marcel, I am afraid on MC68008, storing values to effective address is not possible, as the effective address has to be loaded first. While I believe on later MC processors it is allowed. move.l a0,bad on MC68008 above come as two instructions lea bad,a1 move.l a0,(a1) Tomas

Hi, Thank you, this helps. How about the snippet TWO, any room for optimisation? Coded in C language *bad++ = d7; red_fail movea.l bad,a0 ;Recover Bad Ptr list move.b d7,(a0) ;Mark failing sector lea bad,a0 ;Increment Bad Ptr addq.l #$01,(a0) movea.l image,a1 ;Reset Image Ptr bra.s sec_loop ;Read ne...

Hi, Thank you all for your suggestions, while I might be well within gap timings, I wish to learn to write a neater code. Can this work with negative offset? ONE (a) sec_cont move.w #-514,d3 ;Offset(-) to File-Blk move.b d1,$00(a1,d3.w) ;Record File Number move.b d2,$01(a1,d3.w) ;Record Block Number...

Hi, I am now toying with dumping, the reverse task to MDV copying. My code seems doing things, but I am looking into ways of possible optimisation of the two assembly snippets down here, in the hope to get shorter execution in between gaps. ONE sec_cont suba.l #514,a1 ;Point Image Ptr to File-Blk mo...

Hi,

Very interesting idea, I woudl like to pursue as well. Once having a jig to cut VHS in stripes, spooling a new tape in, how to actually go about glueing both ends into a loop?

Tom

Hi, Rather belatedly, I found this interesting post. On first reading I initially thought, there must be a difference between MD unit Iss#5 coming from Iss#5 QL and MD unit Iss#6. I checked the wiring diagram of both MD Units Iss#5,6, they appear the same, visually they only differ in Headboard PCB,...

Hi Charles, Thank you, I believe with my tools, I can set the loop time in between 7.0 - 7.25, as the precision of my measurement currentlty is <0.25 secs. A small advantage is, I measure it with a real motor load on real cartridges. I would also like to make a jig as per ink pen drawing, but I lack...

Hi,

I have found this piece of information in QL Concepts Manual.

Physically each Microdrive cartridge contains a 200 inch loop of high quality video tape which is moved at 28 inches per second. The tape completes one circuit every 7.5 seconds.

200" / 28"/s = 7.14secs

Tomas

Hi,

Thank you all for your continued support in my quest.

Here is the mod documented in QL Service Manual, I am curious what does it actually rectify in electronic sense. Is it to do with powering MD units, or rather to do with head frequencies used? Many thanks
Tomas

Hi, I did a new measurement as suggested, 4 times a complete loop, than I take the average. Only one test per cart/drive may perhaps be enough now. cart# MDV1 secs/rpm MDV2 secs/rpm 1 7/2310 6.75/2396 2 6.75/2396 6.75/2396 3 7/2310 7/2310 4 6.75/2396 6.75/2396 I was hoping to see clearly that drive ...