IS200DTAIH1ACC IS210DTAOH1AA燃機(jī)模塊，GE使用進(jìn)展
DRAM可通過MC68030、PCC、LANCE和VMEbus。它專門針對MC68030進(jìn)行了優(yōu)化。MVME147-010上未實現(xiàn)奇偶校驗功能。MVME147具有奇偶校驗，在三個用戶中的一個用戶中運行可選模式。在模式1中，不執(zhí)行奇偶校驗，DRAM工作以最大速度。
在模式2中，對所有總線主機(jī)和當(dāng)MC68030為總線時，DRAM以最大速度運行主人當(dāng)模式2中出現(xiàn)奇偶校驗錯誤且MC68030為在本地總線主控器中，總線錯誤信號在當(dāng)前周期。
IS200DTAIH1ACC IS210DTAOH1AA燃機(jī)模塊總線錯誤在所有后續(xù)事件中激活MC68030 DRAM周期。通知所有其他總線主控器奇偶校驗當(dāng)前周期中的錯誤，因此其DRAM訪問時間增加1個時鐘。在模式3中，對所有總線主機(jī)和在當(dāng)前周期內(nèi)報告奇偶校驗錯誤。在這種模式下DRAM訪問時間延長一個時鐘周期，以允許奇偶校驗檢查。
MC68030 DRAM訪問MC68030是默認(rèn)的本地總線主機(jī)，因此它是本地總線總線主控，只要沒有其他設(shè)備請求本地總線主控。PCC DRAM訪問當(dāng)PCC需要傳輸數(shù)據(jù)時，它請求本地總線GCC多端口仲裁器的主控權(quán)。當(dāng)PCC被授予本地總線主控權(quán)后，它執(zhí)行一個總線周期然后釋放總線主控權(quán)。如果在測試過程中檢測到奇偶校驗錯誤PCC到DRAM的讀取周期，總線錯誤返回到PCC。功能描述當(dāng)VMEbus map解碼器檢測到車載DRAM選擇時，VMEchip從GCC請求本地總線主控多端口仲裁器。當(dāng)GCC多端口仲裁器已授予本地總線主控，發(fā)生DRAM讀寫循環(huán)，并且
VMEchip激活DTACK*（或BERR*，如果啟用奇偶校驗，并且VMEbus上出現(xiàn)奇偶校驗錯誤）信號。
Onboard DRAM
The DRAM is accessible by the MC68030, PCC, LANCE, and
VMEbus. It is specifically optimized for the MC68030.
The parity feature is not implemented on the MVME147-010.
The MVME147 has parity check which operates in one of three user
selectable modes.
In mode 1, no parity checking is performed and the DRAM operates
at maximum speed.
In mode 2, parity checking is performed for all bus masters and the
DRAM operates at maximum speed when the MC68030 is bus
master. When a parity error occurs in mode 2 and the MC68030 is
the local bus master, the bus error signal is not activated during the
current cycle. The bus error is activated during all subsequent
MC68030 DRAM cycles. All other bus masters are notified of parity
errors during the current cycle, consequently their DRAM access
time increases by 1 clock.
In mode 3, parity checking is performed for all bus masters and
parity errors are reported during the current cycle. In this mode, the
DRAM access time is extended by one clock cycle to allow for parity
checking.
MC68030 DRAM Accesses
The MC68030 is the default local bus master, therefore it is the local
bus master as long as no other device requests local bus mastership.
PCC DRAM Accesses
When the PCC needs to transfer data, it requests local bus
mastership from the GCC multiport arbiter. When the PCC has
been granted local bus mastership, it executes one bus cycle and
then releases bus mastership. If a parity error is detected during a
PCC to DRAM read cycle, a bus error is returned to the PCC.
Functional DescriptWhen the VMEbus map decoder detects an onboard DRAM select,
the VMEchip requests local bus mastership from the GCC
multiport arbiter. When the GCC multiport arbiter has granted
local bus mastership, a DRAM read or write cycle happens and the
VMEchip activates the DTACK* (or BERR* if parity is enabled and
a parity error occurs) signal on the VMEbus.
