ZXNet эхоконференция «code.zx»

Типичное описание ВГшки. Только для тех, кто по этой фене что-либо понимает.

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FDC 179X documentation
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COMMAND SUMMARY

TYPE COMMAND 7 6 5 4 3 2 1 0
I Restore 0 0 0 0 h v r1r0
I Seek 0 0 0 1 h v r1r0
I Step 0 0 1 u h v r1r0
I Step In 0 1 0 u h v r1r0
I Step Out 0 1 1 u h v r1r0
II Read Sector 1 0 0 m S E C 0
II Write Sector 1 0 1 m S E C a0
III Read Address 1 1 0 0 0 E 0 0
III Read Track 1 1 1 0 0 E 0 0
III Write Track 1 1 1 1 0 E 0 0
IY Force Interr.1 1 0 1 I3I2I1I0

FLAG SUMMARY

TYPE I COMMAND

h = Head Load Flag(Bit 3)
h = 1, Load head at beginning
h = 0, Unload head at beginning
v = Verify flag (Bit 2)
V = 1, Verify on destination track
V = 0, No verify
r1r0 = Stepping motor rate (Bits 1-0)
Refer to table I for rate summary
u = Update flag (Bit 4)
u = 1, Update track register
u = 0, No update

TYPE II & III COMMANDS

m = Multiple record flag (Bit 4)
m = 1, Multiple records
m = 0, Single record
a0 = Data address mark (Bit 0)
a0 = 0, FB (Data mark)
a0 = 1, F8 (Deleted data mark)
E = 15 ms delay (2 MHz)
E = 1, 15 ms delay
E = 0, no 15 ms delay
S = Side select flag
S = 1, Compare for side 0
S = 0, Compare for side 1
C = Side compare flag
C = 0, disable side select compare
C = 1, enable side select compare

TYPE IY COMMAND

II = Interrupt condition flags (Bits 3-0)
I0 = 1, Not-ready to ready transition
I1 = 1, Ready to not-ready transition
I2 = 1, Index Pulse
I3 = 1, Immediate Interrupt
I3-I0 = 0, Terminate with no interrupt

PROCESOR INTERFACE

PIN3 PIN6 PIN5 PIN4 PIN2
CS A1 A0 R/=0 W/=0
0 0 0 status command
0 0 1 track track
0 1 0 sector sector
0 1 1 data data
1 X X H1-Z H1-Z

DELAY AFTER WRITE TO COMMAND REG BEFORE READ STATUS

MFM = 14 mks
FM = 28 mks
*NOTE tymes double for 5" drive

ADDRESS READED BY READ ADDRESS COMMAND

TRACK SIDE SECTOR CRSLENGTH CRC1 CRC2

STATUS REGISTER FORMAT

D7 = 1 Ready\n
D6 = ?
D5 = ?
D4 = 1 Sector not found
D3 = 1 CRC error
D2 = 1 Deleted data mark
D1 = 1 Data request
D1 = 1 Busy

Command Usage
Seek Command - Track reg = Actually Track
Data reg = Destination Track
Read Address - After it Sector reg contains Track #
Write Track - Terminated by index pulse

NOMINAL VS. WORSE CASE SERVICE TIME

density nominal transfer tyme worstcase tyme
read write

single 64 mks 55.0 mks 47.0 mks
double 32 mks 27.5 mks 23.5 mks


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W!7h Be57 W!5hE5, FK0.


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