Network Router User Manual

TMS380C26
NETWORK COMMPROCESSOR
SPWS010A–APRIL 1992–REVISED MARCH 1993
POST OFFICE BOX 1443 • HOUSTON, TEXAS
77251–1443
75
PARAMETER MEASUREMENT INFORMATION
68xxx DIO read timing
NO. PARAMETER MIN MAX UNIT
255 Delay from SDTACK low to either SCS, SUDS, or SLDS high 15 ns
259
†
Hold of SAD high-impedance after SUDS or SLDS low (see Note 21) 0 ns
260 Setup of SADH0–SADH7, SADL0–SADL7, SPH, and SPL valid before SDTACK low 0 ns
261
†
Delay from SCS, SUDS, or SLDS high to SADH0–SADH7, SADL0–SADL7, SPH, and SPL
high-impedance (see Note 21)
35 ns
261a Hold of output data valid after SUDS or SLDS no longer low (see Note 21) 0 ns
267 Setup of register address before SUDS or SLDS no longer high (see Note 21) 15 ns
268 Hold of register address valid after SUDS or SLDS no longer low (see Note 22) 0 ns
272 Setup of SRNW before SUDS or SLDS no longer high (see Note 21) 15 ns
273 Hold of SRNW after SUDS or SLDS high 0 ns
273a Hold of SIACK high after SUDS or SLDS high 55 ns
275 Delay from SCS, SUDS, or SLDS high to SDTACK high (see Note 21) 35 ns
276
‡
Delay from SDTACK low in the first DIO access to the SIF register to SDTACK low in the immediately fol-
lowing access to the SIF
4000 ns
279
†
Delay from SUDS or SLDS high to SDTACK high impedance 65 ns
282a Delay from SDBEN low to SDTACK low 35 ns
282R
Delay from SUDS or SLDS low to SDBEN low (see TMS380 Second Generation Token-Ring User’s
Guide,
SPWU005, subsection 3.4.1.1.1) provided the previous cycle completed
55 ns
283R Delay from SUDS or SLDS high to SDBEN high (see Note 21) 35 ns
286 Pulse duration, SUDS or SLDS high between DIO accesses (see Note 21) 55 ns
†
This specification is provided as an aid to board design.
‡
This specification has been characterized to meet stated value.
NOTES: 21. The “inactive” chip select is SIACK
in DIO read and DIO write cycles, and SCS is the “inactive” chip select in interrupt acknowledge
cycles.
22. In 80x8x mode, SRAS may be used to strobe the values of SBHE
, SRSX, SRS0–SRS2, and SCS. When used to do so, SRAS must
meet parameter 266a, and SBHE
, SRS0–SRS2, and SCS must meet parameter 264. If SRAS is strapped high, then parameters
266a and 264 are irrelevant, and parameter 268 must be met.